Hello CScience,
Just back from holidays, sorry for the late answer.
I had to modify 3+ files to add custom taxonomy support. Still have one bug : the tags filter in archive page is no more usable as the customisation with the CPT overrides something that I didn’t identify well at this time (I suppose in the JS).
The website where I will use this stills in development, then the process is not fully ok at this time.
The files are these :
wpdm-archive-page/assets/js/scripts.js (can be dequeued and custom version requeued, then ok with plugin updates)
The template of the archive page (that can be an override in theme files, then ok with plugin updates)
wpdm-archive-page/src/__/__.php class (can be extended and then be update-proof but didn’t made it at this time)
It’s a too long work to describe the process here, but I can send you the files by PM if you want.