UI: use English localization as a fallback when a string has no trans…

…lation

Sources/WireGuardApp/LocalizationHelper.swift

@@ -3,10 +3,17 @@
 
 import Foundation
 
+/// Gets the English string from the Base.lproj bundle, which can be used as a fallback when the translation for a certain language is missing.
+func tr_base(_ key: String) -> String {
+	let baseBundlePath: String? = Bundle.main.path(forResource: "Base", ofType: "lproj")
+	let baseBundle: Bundle? = Bundle(path: baseBundlePath ?? "") ?? nil
+	return baseBundle?.localizedString(forKey: key, value: nil, table: nil) ?? key
+}
+
 func tr(_ key: String) -> String {
-    return NSLocalizedString(key, comment: "")
+	return NSLocalizedString(key, value: tr_base(key), comment: "")
 }
 
 func tr(format: String, _ arguments: CVarArg...) -> String {
-    return String(format: NSLocalizedString(format, comment: ""), arguments: arguments)
+	return String(format: NSLocalizedString(format, value: tr_base(format), comment: ""), arguments: arguments)
 }