Do German universities internally track the scientific output of single work groups/professors and with which internal/external goals?
I would ask your professor, other professors, or people you know in the administration. Presumably, they know how these evaluations are done in your University.

My experience, in a research institute in Germany, is that faculty is evaluated on both output and grants obtained. Similarly, the institute as a whole is evaluated on these points. Typically, professors try to publish as high as possible here, with much less regard for number of papers published. This is reflected in tenure decisions.