Thanks for the tip!
I managed to find a good workflow with another of the plugins from that repo:
modifyonimport:
modify_album_items:
bad:1:
'': 'bad=1'
during import, if an album matches the “bad:1” query (which i set with the --set config option when launching the import) it sets bad=1 on all the items of said album. That way the path rules are applied as expected.
The plugin is a bit verbose on the console but I can manage for the few albums I’m left with