"How to use the catalog" will go into the Community post I will make once it becomes officially available on lsst-dev. But what sort of Config settings are necessary to get useful matches and fits from it is something else entirely.

I have done that due diligence by eye, but not in a programmatic manner (e.g., I can't point to a script I used to validate things).

From me I'm happy enough to call this "Reviewed"

Yusra AlSayyad: do you want to look at anything or say anything here, or can I close this and move on to putting the new refcat in place?

Yusra is out on vacation this week.

I think it's appropriate to close this ticket as “done”, with a standing invitation to her to raise any lingering concerns she has when she returns.

Following John Swinbank's suggestion, I'm marking this Done. Sorting out how to use this refcat in production is a whole other kettle of fish.