Yup. That's how it works. Thanks to all!!

Over a period of 5 minutes online: (sorry CPH-Flyer, I'm *not* getting an agent involved in this)
Booked a dummy booking *elsewhere* (so I knew what to cancel -- or not, depending if I wanted a night at the fancy place)
Booked real booking for the titanium choice
Cancelled booking at fancy place. (ah well!)
85k cert confirmed back in account. (yscleo, I didn't suffer your fate!)

Yup, more complex but now I'm a pro and can handle the uncertainty of refunding certs and idiosyncrasies of the bonvoy system.

Now if I could only get the app to have my "USD" price default to stick, have it always show stuff with fees included(!), and automatically populate the best price when my corporate code is either more expensive or unavailable..... but that's for a different thread.