I don't understand what you want the community to do about this.  Seems to me that the issue is between you and phantastisch, and he feels that your translation was sub-par.  It also seems to me that if you're going to get paid to do a translation, you ought not make as many mistakes as he claims you made and the ones you admitted to.  

If you're truly qualified to translate something, there should be pretty much zero mistakes--if there are, it indicates that you don't know both languages good enough to take on the job.  In any case, there's no much anyone here is going to do for you.  It's not like anyone can do anything except possibly Theymos, and I highly doubt he's going to get involved in this beef.
Well he doesn't think you did a good job, so there's not much anyone but him can do about it.  I can't evaluate your translation myself, as I don't know German.  There's been a lot of shitty translation jobs by people who aren't qualified to do them, so people are getting very irritated when they see stuff they don't think is good.  Maybe he'll reply to you here, who knows.