Dukemon: A quick workaround to play the remaster in your own (European) language.

The file optionsCustom.txt must be located in the folder: %AppData%...Local...Sacred2Remaster.
Simply press the WIN key+R and enter %AppData% in the field.
I have no idea why the GoG version does not create this file automatically, but Sacred 2 Remaster does not offer any options for this in the game. However, all supported European languages are installed.
Either copy it from the %AppData%...Local...Ascaron Entertainment...Sacred 2 folder
Or simply create a txt file yourself with the following content:

optionsCustom.txt

locale.language = ‘de_DE’
locale.speech = ‘de_DE’

This settings are for the German language.
Optionally, replace the value with

en_UK for English
es_ES for Spanish
fr_FR for French
it_IT for Italian