the_mister_banana: GOG Version is just available in English & Russian ATM.

There is a way to - at least - translate the text into your specific native language without tampering any copyrights:

Extract them from the original retail version patch Installers !

1 - Download the specific V1.06 patch for your language.
2 - Extract the contents of the Installer into separate folder. (7zip will work fine for this) You should get a abundant bunch of files - but you will only need: data1.cab, data2.cab and data1.hdr
3 - Download and install UniExtract from legroom.net
4 - Extract data1.cab with UniExtract. You will get the contents of the patch.
5 - Overwrite the game "Res" folder with the extracted "Res" folder. Or at least these files: texts.res, textslmp.res
6 - Profit !

This will of course only work, when your language got some text updates ...

Also I don't know in which languages the game has been translated to - I couldn't find any sort of a list.
I just know that there is a german version. (Text & Voice translated)