After a little over a week outdoors again, Leo's still doing fine. I noticed a new spray mark on the sliding glass doors recently & I expect that's Leo's work, which reinforces my decision to let him live outside. He's reverting to his old feral self--the way he was before I brought him into the house--which is, of course, for the best. He still likes a headrub, though. And Mom's still a bit depressed about the whole situation, especially when Leo meows at the door to be let in, which he does fairly often.
Minnie is coming to my bed every night now--like Leo, she's getting back to where she was before Leo came inside. That's a welcome development.