Multi language installer innosetup.

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InnoSetup

[Languages]
Name: "french"; MessagesFile: "compiler:Languages\French.isl"
Name: "german"; MessagesFile: "compiler:Languages\German.isl"
Name: "english"; MessagesFile: "compiler:Default.isl"
#define SUPPORTED_LANGS "French,German,English"
#if SUPPORTED_LANGS != ''
#pragma message "Supported languages: " + SUPPORTED_LANGS
#else
#pragma message "Supported languages: no restriction"
#endif
#pragma

LanguageSelected := ExpandConstant('{language}');
case LanguageSelected of
'french':
begin
#include "fr.isl"
end;
'german':
begin
#include "de.isl"
end;
else
begin
#include "en.isl"
end;
end;
here based on the selected language .user needs to display current translation text

What I have tried:

[Languages]
Name: "french"; MessagesFile: "compiler:Languages\French.isl"
Name: "german"; MessagesFile: "compiler:Languages\German.isl"
Name: "english"; MessagesFile: "compiler:Default.isl"
#define SUPPORTED_LANGS "French,German,English"
#if SUPPORTED_LANGS != ''
#pragma message "Supported languages: " + SUPPORTED_LANGS
#else
#pragma message "Supported languages: no restriction"
#endif
#pragma

LanguageSelected := ExpandConstant('{language}');
case LanguageSelected of
  'french':
    begin
      #include "fr.isl"
    end;
  'german':
    begin
      #include "de.isl"
    end;
  else
    begin
      #include "en.isl"
    end;
end;