imo, there should be automatic tags like "active", "abandoned", "maintainer changed recently", "updated after hiatus" and a few more.

The arch devs and community can decide on the time frames. It's not going to be perfect, but it may help warn users of the changes and so they can do a double take.

Anything other than the "active" ones should show what changed (paru already does this) and users should make a conscious choice to install it anyway. (y/N) instead of going through the installation spamming the return key.

AUR does have a voting system, albeit a basic one.

It is my speculation based on experience and direct invitations to review stuff that Google effectively does ranked crowd-sourcing for Google Maps, etc., in which Google secretly tracks and gives heftier vote power to veteran accounts with longer histories of competence and reliability (especially, say, accounts that are a decade old and still regularly contributing and proposing corrections), unbeknownst to said account holders themselves. Perhaps their lead could be the way out of such messes.