I will add this to WIKI. I have one additional note. I don't know if it's the case with Mint, but there are distributions that install flatpak by default.Then the backup directory is where you specify.But the mentioned path is always used with flatpak.
in the QLog wiki, the path for the QLog backup files, the database and the settings is specified under "Autobackup".
The information does not apply if QLog is installed as a Flatpak. In Linux-Mint you can find the database for example under "~/.var/app/io.github.foldynl.QLog/data/hamradio/QLog"
I do not know whether this is the case in all cases. Maybe you could add the paths in the wiki at this point.