I had interrupted the Sleep setup because I realized I sleep all weird anyway, so who cares. :D
Meanwhile I'm halfway through applying apple's "fix" and I'm wondering if I haven't messed it up — it's still restoring apps and I already went to restore the watch, which asked me for my basic health data (height, weight, desired calories...). Turns out that the Health data hasn't been downloaded yet: if I open the Health app on the phone, I get "Downloading Health Data". Same for the Activity app: "Restoring Activity data from iCloud".
You'd think it's downloaded first as it's a system thing, but apparently random apps have priority.
The watch just completed setting up and Activity there shows all zero, as if I just started the day.
I wonder if my health data will be correctly merged when it's finally downloaded, or if it'll just compound the mess.
I've been an Apple user since 2001... their stuff is absolutely great when "it just works", but when something starts going wrong it's a disaster.