My only experience with German language comics dates back to 1967 or so, when one of my cousins brought a few back from Germany after being stationed there with the United States Air Force for three years. He was married and his first child was born in Germany; she bought and read a lot of Disney reprints to augment her efforts to learn German and she became much better with the language than her husband. She brought some of comics back with her, some featured Disney exclusively and she thought they were a mixture of American stories reprinted with German text, some reprints from European Disney books featuring stories by European writers and artists, and (she thought) maybe some stories by Germans. I did recognize a few of the Donald Duck stories as reprints from Dell Comics of the late fifties, and the others were new to me. She also had a couple of books that were non-Disney and were probably reprinted French western comics. As I recall these anthology comics featured several different characters, the stories were chapters of long stories (or possibly even newspaper strips), and I found them fascinating because I had very little knowledge of German then (and not much more now) and it was a challenge to figure out not only what was going on but what the main plot might be. I don't know if any material by German writers/artists were included or not. I'm fairly sure one of the characters was Lucky Luke because the cartoon art style is distinctive. I'm not sure about the other characters or where they were from.
I've enjoyed the discussion, although I have no real personal knowledge of the subject.