Always check translation list for unmapped characters when opening language drop-down

We still avoid the stutter from loading the files each time, but since translation name characters  only end up in the persistent extra string list if they're missing in the currently loaded translation, we need to check for those always or at least after switching translations.

Author: elvissteinjr

src/DesktopPlusUI/WindowSettings.cpp

@@ -786,10 +786,13 @@ void WindowSettings::UpdatePageMainCatInterface()
             static int list_id = 0;
 
             //Load language list when dropdown is used for the first time
-            if ( (ImGui::IsWindowAppearing()) && (list_langs.empty()) )
+            if (ImGui::IsWindowAppearing())
             {
-                list_id = 0;
-                list_langs = TranslationManager::GetTranslationList();
+                if (list_langs.empty())
+                {
+                    list_id = 0;
+                    list_langs = TranslationManager::GetTranslationList();
+                }
 
                 //Select matching entry and add unmapped characters if needed
                 const std::string& current_filename = ConfigManager::GetValue(configid_str_interface_language_file);