install game in spanish, then download the archive from first post
edit the iss script & change the following language (in bold ) to match yours.
Just follow the instructions I wrote, with the file from post #1.
Code:
Root: HKLM; SubKey: "SOFTWARE\{code:GetAppPublisher}\{code:GetAppName}"; ValueType: string; ValueName: Language; ValueData: ENU; Flags: UninsDeleteKey;