This bug isn't really a bug, found the resolution today:
The settings which I claimed to be missing/ignored in cups-pdf are now available in job specific settings of the printing dialog (xfce4 desktop) and are persistent thus surviving reboots. This was absolutely different compared to how it was in Bullseye where there was no such possibility neither in the printing dialog nor in the settings of the printing object on the desktop. As this is a complete fresh installation of Bookworm there was no such notification during install. Also explanations in cups-pdf.conf do not mention that change. Sorry, Alf
