They have been for a while now. It started before the API thing with subreddits that were basically mirrors of English ones. But (badly) auto translated into German.
A few weeks ago, the Google results got flooded with auto translations. You can still find stuff that was written in German, but you have to limit the search to German subs (site:reddit.com/r/de, for example).
Or check the sub name in the search results. If it’s in German, you should be good. If it’s in English, or if it doesn’t show up at all, it’s usually a machine translation.
For me, it would have to be something nice, but not so interesting that I want to stay awake (Ariadne auf Naxos). Or something I’ve heard a million times (The Magic Flute).
Beethoven has always been calming for me, so maybe Fidelio too.
If you’re looking for beautiful music, maybe Tosca or Rusalka.
There are others that I wouldn’t necessarily fall asleep to, like Don Carlo, Pagliacci, Rigoletto, or La Traviata. This is a pretty good list of some of the best known operas.