Well, for one thing Tutufix has not been translated to German. So you might have other issues with it, including part of your game being in English and part in German.
If you can live with that and want to proceed, open up setup-tutufix.tp2 in a text editor and add to the ALLOW_MISSING section around line 13:
~_ingwolf.itm~
If that doesn't work, you can skip it more forcefully by commenting out the section. Add a /* before the COPY_EXISTING after the // WOLFWERE REGEN FIX (~ line 1086) and a */ after the BUT_ONLY_IF_IT_CHANGES (~ line 1093).
But as I said, you may run into more issues which you may need to deal with similarly.
Oh and before you go further, did you apply the latest
Bioware patches to your version of the game (both BG1 and BG2) before converting to Tutu?