• Add RESX files to project (See Localization Using ResX Files).
• Edit class AHI.App.Localization.TLocalizationTools in src\AHI.App.Localization\Tools.cs to include new supported language:

  public static ObservableCollection<TLanguageInfo> SupportedLanguageInfo = new ObservableCollection<TLanguageInfo>() 
          { 
              //new TLanguageInfo() {LanguageNative = Resources.rsLangBulgarian,  LanguageEnglish = "Bulgarian",  LanguageCode = "bg-BG"},
              //new TLanguageInfo() {LanguageNative = Resources.rsLangDanish,     LanguageEnglish = "Danish",     LanguageCode = "da-DK"},
              new TLanguageInfo() {LanguageNative = Resources.rsLangEnglish,    LanguageEnglish = "English",    LanguageCode = "en-US"},
              //new TLanguageInfo() {LanguageNative = Resources.rsLangFrench,     LanguageEnglish = "French",     LanguageCode = "fr-CA"},
              //new TLanguageInfo() {LanguageNative = Resources.rsLangGerman,     LanguageEnglish = "German",     LanguageCode = "de-DE"},
              new TLanguageInfo() {LanguageNative = Resources.rsLangKorean,     LanguageEnglish = "Korean",     LanguageCode = "ko-KR"},
              new TLanguageInfo() {LanguageNative = Resources.rsLangItalian,    LanguageEnglish = "Italian",    LanguageCode = "it-IT"},
              new TLanguageInfo() {LanguageNative = Resources.rsLangSpanish,    LanguageEnglish = "Spanish",    LanguageCode = "es-ES"},
              //new TLanguageInfo() {LanguageNative = Resources.rsLangPortuguese, LanguageEnglish = "Portuguese", LanguageCode = "pt-BR"},
              //new TLanguageInfo() {LanguageNative = Resources.rsLangRussian,    LanguageEnglish = "Russian",    LanguageCode = "ru-RU"},
              //new TLanguageInfo() {LanguageNative = Resources.rsLangTurkish,    LanguageEnglish = "Turkish",    LanguageCode = "tr-TR"},
              //new TLanguageInfo() {LanguageNative = Resources.rsLangPolish,     LanguageEnglish = "Polish",     LanguageCode = "pl-PL"},
          };

• Editing RESX Files with SimpleResxEditor

• Open InnoSetup installer script.
• Add a directive to define language:

  sysutils.iss

  #if AppLangSupp == "<LanguageNameHere>"
    #define <LanguageNameHere>
    ...
  #elif...
  #else
    #define English
  #endif

• Add Language resources under section [Languages]:

  sysutils.iss

  [Languages]
  #ifdef English
  Name: English; MessagesFile: compiler:Default.isl
  #endif
  #ifdef <LanguageNameHere>
  Name: <LanguageNameHere>; MessagesFile: compiler:Languages\<LanguageNameHere>.isl
  #endif

• Add and translate resource strings under section [CustomMessages]:

  sysutils.iss

  [CustomMessages]
  #ifdef English
  SelectDrivers=Select Drivers
  ...
  #endif
  ; <LanguageNameHere> should be replaced by the target language to localize
  #ifdef <LanguageNameHere>
  ;<LanguageNameHere>.String=<TranslatedString>
  <LanguageNameHere>.SelectDrivers=Seleccionar Controladores
  ...
  #endif

Syntax for resource strings to translate:

; <LanguageNameHere>
<LanguageNameHere>.<ResourceStringName>=<ResourceStringValueToTranslate>
...

Example

; English (Default)
rsSelectDrivers=Select Drivers

; Spanish
Spanish.rsSelectDrivers=Seleccionar Controladores
...