I received a notification that there was an upgrade available. And I ran it. And it worked.
Well, that solves a number of issues, but not the principal ones: governance, flexibility, and control of the setup, especially the email setup.
So we’re almost ready to move on to https://socialhub.activitypub.rocks/. If you did not already make your move there, and want to transfer your stuff from here to there, PM me and I’ll get you sorted.