MagikGimp: You've purchased the game(s) on GOG but the other language versions haven't been offered to you. I see no reason therefore why you don't have the right to download the games from "abandonware" sites in the language you want. The majority of old releases on GOG are the cracked versions anyway--GOG wouldn't be so very successful IMHO if it weren't for the pirates' work back in the day, ironically--; you're just giving money to whoever holds the licencing rights now (which is very rarely the original publishers or distributors) and GOG. The files are therefore identical.
Of course, I very much doubt I can post any links to downloads here but I know for sure there is a French site with the games and I should expect for German, Spanish and maybe even Polish somewhere too.
Diffrent publishers and therefore different copyright holders are a good reason.
For example: Softgold published several point&click adventures in Germany, sometimes they also did the translation. So they are to be contacted for german versions of these games, not whichever studio actually created the original game.
But really, no one gives a ****. Just grab it from wherever you want, your conscience should be ok if you bought it here.