Dave
Antix23-desktop-files has a bunch of desktop files with updated translations for various programs. These are then implemented in the system through using dpkg divergent. If I recall correctly this is to avoid repackaging a number of packages to update translations that the original program / packager does not include for various reasons.
Perhaps there is an issue with a how dpkg divergence is done or how desktop-defaults searches for the desktop files through the divergence. I think desktop-menu was altered to handle this. Maybe other programs are also having problems like desktop-defaults-set. Does app-select (or other programs) also have an issue with these packages containing .desktop files in antix23-desktop-files?
Computers are like air conditioners. They work fine until you start opening Windows. ~Author Unknown