I'm a native speaker/writer of both Japanese and Mandarin Chinese. Let me know if I can help!
German in this case, but like I said, I'm pretty sure I can dig up someone locally that does German, so mostly I'm curious about services that do this kind of stuff.
Few tens of strings? I'll give it a try. Just pass over the first, let's say, twenty strings in a follow-up comment. German native speaker here.