Thanks for those tips.
I tried a second example:
internal~Join Group X!~Come join our formerly top secret group.~https://example.com/~group-x
… then checked with both an anonymous session, and also by impersonating a non-admin and non group-x member user account. Unfortunately neither preview showed up including this second confirmation one. For my admin account, it looked OK, appearing directly above the “internal” slug category, as expected, with the correct link destination, etc.
We do have some things that aren’t quite normal seeming with respect to category displays, so it’s possible this is related to that, unless other folks end up finding a similar type of non-expected behavior.