you dont need language packs for that game.
just go to the install dir and look for the file uk_sounds.naz
if you now want another language just change the first two letters of the file to your desired language.
uk = english
es = spanish
fr = french
it = italian
de = german
for example: instead of english ( uk_sounds.naz) try german (de_sounds.naz)
Menu and audio is now in your desired language
C'mon, simple as fuck. Many thanks boss!!! :D
Thanks to the other people too (curious comment jacobmarner hahaha) and, if GOG.com could make a language switcher or something, it would be fine!