I am from the area where this particular sign with the strange track distribution is located, but I just can’t put my finger on it. Dortmund, Essen, Cologne. Must be somewhere here because I’ve seen it so many times! And you’re right, “Zentrum” and “Nordstadt” are pretty generic, that’s why I cannot find it through online searches, I guess.
In case you didn't know or haven't tried yet: AusweisApp2 does exist for Linux. But I assume, like me, you tried unsuccessfully already. For me, the Linux drivers of my card reader don't work…