Don't know if you are already aware, but the TMNT Universal Fanfic Competition has categories for stories in foreign languages - Spanish, French, and German. There is a category for stories in German under the General and Mature ballot. Here is the link for the competition's Tumblr:
tmntuniversalfanficcomp.tumblr…I am also looking for help in translating some of the competition posts into German, as well as checking out stories that are nominated to make sure they are tagged and nominated correctly. I have spoken to come of you already, but I recognize everyone is busy! If you have any interest in helping out, send me a note! Thanks!!!