Hi all,
since GalCiv3 didn't offer a localization on release, except Russian 
, I managed to find a skilled translator on Steam groups.
GermanDogs | N!GHTM4RE | 74 offers the files in his GD Steam Group. Unfortunately he decided to overwrite original english text files.
So I compiled the files into a GermanLocalization MOD for now, which I do rate a little more stable and of course secure.
Download the files HERE , version 1.1
and just extract the folder into C:\Users\{your name}\Documents\my games\GalCiv3\Mods
check 'use mods' in the options and have fun.
Cheers!