Yes, there needs to be a glossary somewhere to get people up to speed, or some kind of on-boarding process. It's also plausible that some of the naming conventions are from translation weirdness, and, as you say, backend Activitypub naming conventions that frontend users don't normally see.
I made a magazine (aka a community, aka a sub[reddit]) specifically so I could play around with kbin to figure things out. Right now, trial and error is all we have, as I imagine all the devs are more busy with more technical issues than naming conventions.