Is the German Armed Forces Proficiency Badge worth promotion points?

No. No foreign badge or award gives promotion points.
The list of badges that do is in AR 600-8-19, table 3-12.

Not according to the RCAS awards printout.

I will add though, if you haven't done it try it. It's fun especially if you get friends to go with you.

Make sure you practice the swim and get good at it if you've never done it before.

The badge itself isn't worth promotion points. However, you can receive an award if you are lucky enough (if another GAFPB event comes around after you obtain the badge) to be cadre for a pre-GAFPB training program, and/or proctor the actual event. A very nice NCOER bullet as well.