This is just a quick fix method. You may want to contact support.

If you have the disk.

Un-install then Re-install the game. Go to where you installed the game and copy the Sound folder (original German sounds).

Place the Sounds folder temporarily on your desktop and update the game again. Test sounds with WinAmp free.

Go to your mods directory and create a folder inside one or all of the expansion folders. Name the folder German or something. Paste the copy of the sounds folder into the new mod folder. You just made a mod.

Enable the mod in game. Sound mods are easily stackable with other mods. Keep the German Sound mod on TOP.

If you play multi-player, don't mess with the original files in the Sins root directory, just copy.

I have not the Trinity pack... just the Sin CD from Kalipso, and Entrenchment/Diplomacy buy online... i have know a similar problem that you with my French version... but it was easily resolved... in my main folder, i have found a huge file ( 146.6 mb ) called French_Movie_Sound.exe ... once i have click on it, it have install all the sound and cinematic in French...

If you are lucky, you will have a similar file for the german in your case, and it is only one click away for enjoy fully these great game in your native language...

Not sure... all file have the same name... and i am not sure that bink or ogg files are checked for online play...

But if you use a french.str or german.str ( text in game ), it is maybe a good idea to use the myfisto mod method...