I looked through the german version of the game, and i "worked" on a little fix for the typos i have found so far, still looking for more. If you played the german version and have suggestions for more changes, then just feel free to post them and i'll fix and upload it asap.
Just extract the file german.lang for the Retail Version to: c:\program files\amnesia the dark descent\redist\config\lang_main
And for the Steam Version to: c:\program files\steam\steamapps\common\amnesia the dark descent\config\lang_main
Changelog for GermanSubtitleFix Version 1.0.0.0