I should’ve tried one more thing before posting, sorry about that.
I clicked on Verify & Repair Database, and it ran and failed.
… which I’m not super worried about because this database does index some stuff on iCloud and I’ve seen this happen once before and I don’t fully understand it but I sort of give it a pass
No immediate change, but after a few more minutes, I now see the “last synchronized” times match up.
So, problem solved.
But while we’re here, if someone ends up reading this, any clues on how to interpret the “failure to repair”? (my gut feeling is that it’s a false negative, but how do I make sure?)