Has anyone had the same problem? I just figured out something very interesting.
If you use the "old" classic IPTC Dialog, you have different shortcuts for "save & move to next".
If you deactivate the classic, you can use a more common shortcut like cmd-B or cmd-N for the same action,
but that works perfectly on a german/ swiss-german keyboard.
Strange, that there are different shortcuts, but hey, I found a way and just wanted to share that with you.
Best swiss nik