fix(gui): route runtime status messages through Loc instead of hardcoded Italian

Send/Donate/Sync/Wizard view models wrote status/error strings
directly in Italian ("Importo non valido.", "Errore: …", the TLS
pin-mismatch message, …), so a user running the app in English/German/
etc. still saw them in Italian despite the 6-language Loc system
covering the rest of the UI.

Added the missing Loc keys and routed every occurrence through
Loc.Tr(...). CertificatePinMismatchException (Core) no longer bakes an
Italian message into .Message; it now exposes Host/Port so the UI can
translate it, with an English fallback for any exception type the UI
doesn't specifically handle. Also drops the now-stale USERGUIDE.md
caveat about a few messages staying in Italian regardless of language.

USERGUIDE.md

@@ -583,8 +583,7 @@ The Settings overlay (gear icon / menu *Settings*) contains exactly two preferen
 the door to the server settings:
 
 - **Language** — Italiano, English, Español, Français, Português, Deutsch. Applies
-  immediately. Default: English. (A few low-level error messages are currently shown in
+  immediately. Default: English.
-  Italian regardless of language.)
 - **Amount unit** — how amounts are displayed *and interpreted when you type them*:
 
   | Unit | In satoshi | Decimals shown |

src/App/Localization/Loc.cs

@@ -403,6 +403,24 @@ public sealed class Loc
             "Certificados SSL redefinidos: tente novamente a conexão.",
             "SSL-Zertifikate zurückgesetzt: Verbindung erneut versuchen."],
         ["msg.error"]             = ["Errore",                                                            "Error",                        "Error",                                "Erreur",                                   "Erro",                                     "Fehler"],
+        ["msg.broadcast.error"]   = ["Errore broadcast",                                                  "Broadcast error",              "Error de transmisión",                 "Erreur de diffusion",                      "Erro de transmissão",                      "Übertragungsfehler"],
+        ["msg.peer.discovery.error"] = ["Errore nella scoperta peer",                                     "Peer discovery error",         "Error al descubrir peers",             "Erreur de découverte des pairs",           "Erro na descoberta de peers",              "Fehler bei der Peer-Suche"],
+        ["msg.peer.discovery.found"] = ["Trovati {0} nuovi server dai peer (totale {1}).",                "Found {0} new servers from peers (total {1}).", "Se encontraron {0} nuevos servidores de peers (total {1}).", "{0} nouveaux serveurs trouvés via les pairs (total {1}).", "Encontrados {0} novos servidores dos peers (total {1}).", "{0} neue Server von Peers gefunden (insgesamt {1})."],
+        ["msg.peer.discovery.none"] = ["Nessun nuovo server annunciato (totale {0}).",                    "No new servers announced (total {0}).", "No se anunciaron nuevos servidores (total {0}).", "Aucun nouveau serveur annoncé (total {0}).", "Nenhum novo servidor anunciado (total {0}).", "Keine neuen Server angekündigt (insgesamt {0})."],
+        ["msg.send.sync.first"]  = ["Sincronizza prima di inviare.",                                     "Synchronize before sending.",  "Sincroniza antes de enviar.",          "Synchronisez avant d'envoyer.",            "Sincronize antes de enviar.",              "Vor dem Senden synchronisieren."],
+        ["msg.send.connect.first"] = ["Connettiti al server e sincronizza prima di inviare.",             "Connect to the server and synchronize before sending.", "Conéctate al servidor y sincroniza antes de enviar.", "Connectez-vous au serveur et synchronisez avant d'envoyer.", "Conecte-se ao servidor e sincronize antes de enviar.", "Mit dem Server verbinden und vor dem Senden synchronisieren."],
+        ["msg.amount.invalid"]   = ["Importo non valido.",                                               "Invalid amount.",              "Importe no válido.",                   "Montant invalide.",                        "Valor inválido.",                          "Ungültiger Betrag."],
+        ["msg.feerate.invalid"]  = ["Fee rate non valido.",                                              "Invalid fee rate.",            "Tarifa no válida.",                    "Taux de frais invalide.",                  "Taxa inválida.",                           "Ungültige Gebührenrate."],
+        ["msg.broadcasted"]      = ["Trasmessa",                                                         "Broadcast",                    "Transmitida",                          "Diffusée",                                 "Transmitida",                              "Übertragen"],
+        ["msg.donate.thanks"]    = ["Grazie! txid",                                                      "Thank you! txid",              "¡Gracias! txid",                       "Merci ! txid",                             "Obrigado! txid",                           "Danke! txid"],
+        ["msg.unsigned.watchonly"] = [" · NON firmata (watch-only)",                                    " · NOT signed (watch-only)",   " · NO firmada (watch-only)",           " · NON signée (watch-only)",               " · NÃO assinada (watch-only)",             " · NICHT signiert (watch-only)"],
+        ["msg.cert.mismatch"]    = [
+            "Il certificato TLS di {0} è cambiato rispetto a quello salvato. Se il server ha rinnovato il certificato, esegui il reset dei certificati SSL.",
+            "The TLS certificate of {0} has changed from the one saved. If the server renewed its certificate, reset the SSL certificates.",
+            "El certificado TLS de {0} ha cambiado respecto al guardado. Si el servidor renovó su certificado, restablece los certificados SSL.",
+            "Le certificat TLS de {0} a changé par rapport à celui enregistré. Si le serveur a renouvelé son certificat, réinitialisez les certificats SSL.",
+            "O certificado TLS de {0} mudou em relação ao salvo. Se o servidor renovou o certificado, redefina os certificados SSL.",
+            "Das TLS-Zertifikat von {0} hat sich gegenüber dem gespeicherten geändert. Wenn der Server das Zertifikat erneuert hat, setzen Sie die SSL-Zertifikate zurück."],
 
         // Contacts
         ["contacts.name"]         = ["Nome",                                                              "Name",                         "Nombre",                               "Nom",                                      "Nome",                                     "Name"],

src/App/ViewModels/MainWindowViewModel.Donate.cs

@@ -3,6 +3,7 @@ using System.Threading.Tasks;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using NBitcoin;
+using PalladiumWallet.App.Localization;
 using PalladiumWallet.Core.Chain;
 using PalladiumWallet.Core.Net;
 using PalladiumWallet.Core.Wallet;
@@ -32,7 +33,7 @@ public partial class MainWindowViewModel
 
         if (_account is null || _doc?.Cache is null || _lastTransactions is null)
         {
-            DonatePreview = "Sincronizza prima di inviare.";
+            DonatePreview = Loc.Tr("msg.send.sync.first");
             return;
         }
         try
@@ -40,7 +41,7 @@ public partial class MainWindowViewModel
             var destination = BitcoinAddress.Create(DevAddress, PalladiumNetworks.For(Net));
             if (!CoinAmount.TryParseIn(DonateAmount.Trim(), _config.Unit, out var amount) || amount <= 0)
             {
-                DonatePreview = "Importo non valido.";
+                DonatePreview = Loc.Tr("msg.amount.invalid");
                 return;
             }
             if (!decimal.TryParse(SendFeeRate, System.Globalization.NumberStyles.Any,
@@ -61,7 +62,7 @@ public partial class MainWindowViewModel
         {
             _pendingDonate = null;
             HasPendingDonate = false;
-            DonatePreview = $"Errore: {ex.Message}";
+            DonatePreview = $"{Loc.Tr("msg.error")}: {ex.Message}";
         }
         await Task.CompletedTask;
     }
@@ -74,7 +75,7 @@ public partial class MainWindowViewModel
         try
         {
             var txid = await _client.BroadcastAsync(_pendingDonate.ToHex());
-            DonatePreview = $"Grazie! txid: {txid}";
+            DonatePreview = $"{Loc.Tr("msg.donate.thanks")}: {txid}";
             DonateAmount = "";
             _pendingDonate = null;
             HasPendingDonate = false;
@@ -82,7 +83,7 @@ public partial class MainWindowViewModel
         }
         catch (Exception ex)
         {
-            DonatePreview = $"Errore broadcast: {ex.Message}";
+            DonatePreview = $"{Loc.Tr("msg.broadcast.error")}: {ex.Message}";
         }
     }
 

src/App/ViewModels/MainWindowViewModel.Send.cs

@@ -3,6 +3,7 @@ using System.Threading.Tasks;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using NBitcoin;
+using PalladiumWallet.App.Localization;
 using PalladiumWallet.App.Services;
 using PalladiumWallet.Core.Chain;
 using PalladiumWallet.Core.Net;
@@ -47,14 +48,14 @@ public partial class MainWindowViewModel
     {
         if (_account is null || _doc?.Cache is null)
         {
-            SendPreview = "Sincronizza prima di inviare.";
+            SendPreview = Loc.Tr("msg.send.sync.first");
             return;
         }
         try
         {
             if (_lastTransactions is null)
             {
-                SendPreview = "Connettiti al server e sincronizza prima di inviare.";
+                SendPreview = Loc.Tr("msg.send.connect.first");
                 return;
             }
 
@@ -62,12 +63,12 @@ public partial class MainWindowViewModel
             long amount = 0;
             if (!SendAll && !CoinAmount.TryParseIn(SendAmount, _config.Unit, out amount))
             {
-                SendPreview = "Importo non valido.";
+                SendPreview = Loc.Tr("msg.amount.invalid");
                 return;
             }
             if (!decimal.TryParse(SendFeeRate, out var feeRate) || feeRate <= 0)
             {
-                SendPreview = "Fee rate non valido.";
+                SendPreview = Loc.Tr("msg.feerate.invalid");
                 return;
             }
 
@@ -78,14 +79,14 @@ public partial class MainWindowViewModel
             SendPreview = $"txid {_pendingSend.Txid[..16]}… · " +
                 $"fee {Fmt(_pendingSend.Fee.Satoshi)} " +
                 $"({_pendingSend.Transaction.GetVirtualSize()} vB)" +
-                (_pendingSend.Signed ? "" : " · NON firmata (watch-only)");
+                (_pendingSend.Signed ? "" : Loc.Tr("msg.unsigned.watchonly"));
             HasPendingSend = _pendingSend.Signed;
         }
         catch (Exception ex)
         {
             _pendingSend = null;
             HasPendingSend = false;
-            SendPreview = $"Errore: {ex.Message}";
+            SendPreview = $"{Loc.Tr("msg.error")}: {DescribeError(ex)}";
         }
         await Task.CompletedTask;
     }
@@ -98,7 +99,7 @@ public partial class MainWindowViewModel
         try
         {
             var txid = await _client.BroadcastAsync(_pendingSend.ToHex());
-            SendPreview = $"Trasmessa: {txid}";
+            SendPreview = $"{Loc.Tr("msg.broadcasted")}: {txid}";
             SendTo = SendAmount = "";
             _pendingSend = null;
             HasPendingSend = false;
@@ -106,7 +107,7 @@ public partial class MainWindowViewModel
         }
         catch (Exception ex)
         {
-            SendPreview = $"Errore broadcast: {ex.Message}";
+            SendPreview = $"{Loc.Tr("msg.broadcast.error")}: {DescribeError(ex)}";
         }
     }
 }

src/App/ViewModels/MainWindowViewModel.Sync.cs

@@ -319,14 +319,14 @@ public partial class MainWindowViewModel
             IsConnected = false;
             ConnectionStatus = Loc.Tr("conn.none");
             ConnectionStatusShort = Loc.Tr("conn.none");
-            StatusMessage = ex.Message;
+            StatusMessage = DescribeError(ex);
         }
         catch (Exception ex)
         {
             IsConnected = _client?.IsConnected == true;
             ConnectionStatus = IsConnected ? ConnectionStatus : Loc.Tr("conn.none");
             ConnectionStatusShort = IsConnected ? Loc.Tr("conn.connectedto") : Loc.Tr("conn.none");
-            StatusMessage = $"Errore: {ex.Message}";
+            StatusMessage = $"{Loc.Tr("msg.error")}: {DescribeError(ex)}";
             if (_account is not null)
             {
                 _syncFailed = true;
@@ -378,7 +378,8 @@ public partial class MainWindowViewModel
         }
         if (temp is null)
         {
-            StatusMessage = $"Errore nella scoperta peer: {lastError?.Message ?? Loc.Tr("conn.none")}";
+            StatusMessage = $"{Loc.Tr("msg.peer.discovery.error")}: " +
+                (lastError is null ? Loc.Tr("conn.none") : DescribeError(lastError));
             return;
         }
         try
@@ -401,15 +402,26 @@ public partial class MainWindowViewModel
             SelectedKnownServer = KnownServers.FirstOrDefault(s => s.Host == selected?.Host)
                 ?? KnownServers.FirstOrDefault();
             StatusMessage = added > 0
-                ? $"Trovati {added} nuovi server dai peer (totale {KnownServers.Count})."
+                ? string.Format(Loc.Tr("msg.peer.discovery.found"), added, KnownServers.Count)
-                : $"Nessun nuovo server annunciato (totale {KnownServers.Count}).";
+                : string.Format(Loc.Tr("msg.peer.discovery.none"), KnownServers.Count);
         }
         catch (Exception ex)
         {
-            StatusMessage = $"Errore nella scoperta peer: {ex.Message}";
+            StatusMessage = $"{Loc.Tr("msg.peer.discovery.error")}: {DescribeError(ex)}";
         }
     }
 
+    /// <summary>
+    /// Translates known Core exception types to the current UI language; falls back to the
+    /// exception's own message (Core has no localization, so it is English by default).
+    /// </summary>
+    private static string DescribeError(Exception ex) => ex switch
+    {
+        CertificatePinMismatchException cert =>
+            string.Format(Loc.Tr("msg.cert.mismatch"), $"{cert.Host}:{cert.Port}"),
+        _ => ex.Message,
+    };
+
     private void OnServerNotification(string method, System.Text.Json.JsonElement payload)
     {
         if (method is "blockchain.scripthash.subscribe" or "blockchain.headers.subscribe")

src/App/ViewModels/MainWindowViewModel.Wizard.cs

@@ -416,7 +416,7 @@ public partial class MainWindowViewModel
         }
         catch (Exception ex)
         {
-            StatusMessage = $"Errore: {ex.Message}";
+            StatusMessage = $"{Loc.Tr("msg.error")}: {ex.Message}";
         }
     }
 
@@ -473,7 +473,7 @@ public partial class MainWindowViewModel
         catch (Exception ex)
         {
             newLock.Dispose();
-            StatusMessage = $"Errore: {ex.Message}";
+            StatusMessage = $"{Loc.Tr("msg.error")}: {ex.Message}";
         }
     }
 

src/Core/Net/ElectrumClient.cs

@@ -284,5 +284,9 @@ public sealed class ElectrumServerException(string error) : Exception(error);
 /// It is unlocked with an explicit reset of the certificates.
 /// </summary>
 public sealed class CertificatePinMismatchException(string host, int port) : Exception(
-    $"Il certificato TLS di {host}:{port} è cambiato rispetto a quello salvato. " +
+    $"The TLS certificate of {host}:{port} has changed from the one saved. " +
-    "Se il server ha rinnovato il certificato, esegui il reset dei certificati SSL.");
+    "If the server renewed its certificate, reset the SSL certificates.")
+{
+    public string Host { get; } = host;
+    public int Port { get; } = port;
+}