I just saw your story and read what you have up so far. My congratulations, you've managed a distinctly different approach here and I'm looking forward to seeing where it goes. I will admit that Harry seems more likely to be come a "Grey" practioner than a Light or Dark one.
Regarding the translations, I like the feel of the German at first but it gets a bit old. You might consider the same approach used in the movie version of "Hunt for Red October" where the Russian sub captain (played by Sean Connery) starts out speaking in Russian with subtitles and finishes speaking, apparently, in English. The equivalent would be a few sentences in German to frame things (with translations in parentheses) and then just the translations in English.
Author's response
Mhm, I probably won't be doing full german translations anymore, just thought English would look silly in a native German market.