Does your library do the thing where it is connected to a bunch of other libraries and you can ask for an English-language version of the book to be sent to your library from another, larger one, which would have it?

Well, I always like reading books in the language they were first written in, if possible.
So maybe read the English-literature books in English, and the German-literature books auf Deutsch.

Nothing lost by trying, anyhow!

Yes, worth a shot! My library does it! The library closest to me is fairly small, but there are 15 or so libraries in my county, and they're all connected. So you can get on their website and browse all the books in the county, then you can put them on hold and even tell them to ship them to your preferred library for pickup for free.

Hehe, yes, I use that feature a lot in the spring and summer! (I don't in the winter because I hate returning things late, but there is too much snow here to commit to returning things on time). The website even tells me when the book is being sent to my library and when it arrives, and then it gives me a week to come get it.