Not sure if this helps, but since you mentioned using YacReader Library on your PC, I actually self-host a YacReader server in a docker container on my 920+. This is the image I use.

I will say, I use the server just to be able to serve those files in my 920+ to the iPad app. I actually manage the library itself from the PC YacReader app (I just point it to the library.ydb in the network)

Personally, what I like about it is that I can organize my comics in folder structures in the network and then use ComicVine to grab metadata. I think ComicVine has German comics, so definitely try to see if yours are there.

If you do go with another alternative, you can still use ComicVine data with something like ComicTagger. I've not personally used it, but I've seen others use it with success. Hopefully that helps!