I was looking for the german version for the gog version and instead of pulling out my 2 CDs from some of the containers with CDs this thread on steam was absolutely helpful for me: steamcommunity.com/sharedfiles/filedetails/?id=1161336852

Edit: It does not allow me to post full http/https links here, please copy the URL above into a new tab

The GOG version has german language already included. No need to do any manual patching.
You can select the language before downloading (english, german, french, spanish)