Thanks. I’ve removed the two files successfully. 
I guess it’s just a copy&paste error and you meant manjaro-gnome-settings 
By the way, I noticed the new update keeps rewriting the faulty ‘gdm’ dconf profile which is listing those missing ‘gdm’, ‘site’ & ‘distro’ databases. Unfortunately this comes with a lot of warning messages in the system journal.
/etc/dconf/profile/gdm
user-db:user
system-db:gdm
system-db:local
system-db:site
system-db:distro
Is there anything I can do, to prevent it rewritten every time manjaro-gnome-settings is updated? I keep deleting the ‘gdm’ profile but is it maybe better to just edit the file and remove those missing system-db? Will updating overwrite an existing ‘gdm’ dconf profile?
Tbh, I don’t know why those required system-db (gdm, site, distro) are missing on my installation. I have never meddled with dconf in the past or removed any system-db voluntarily.