I have created a small projet to test your library.
Create new application. On form1 place tsiLang

Source:
const
rsMessage = 'Hello world';
Procedure Button1Click();
begin
ShowMessage(rsMessage);
end;
Ok, it's really simple ...

After that I launch the wizard and to translate the const, i go to file/const section/with form...
The wizard found my rsMessage, I click replace.
Here's the new modified code:
Const
rsMessage: string = ''; (* Here your message *)
procedure TMainForm.FormCreate(Sender: TObject);
begin
UpdateStrings;
end;
procedure TMainForm.siLangChangeLanguage(Sender: TObject);
begin
UpdateStrings;
end;
procedure TMainForm.UpdateStrings;
begin
rsMessage := siLang.GetTextOrDefault('rsMessage');
end;
Off course when i compile I get error in updatestrings because const are readonly. Why the wizard do bad change to my code ? Why not only put the siLang.GetTextOrDefault('rsMessage'); into the showmessage ?
I hope you can understand my description and show me what I'm doing bad ?
Thanks,
lenif7780