What you call the Garden Spot is just the same as the "back" box when playing UEL.....I suppose.
Indeed, I see sometimes spots where the UEL threads do not move at all either sideways or down/up. I guess when mapping the fairways in 3D the & using UEL the system finds those completely flat spots and shows the black box, but when the lie is not completely 100% flat, is simply does not shows the black box and you see your shots made as in flats.
As you mentioned Cerino, there are many flat spots in Peeble back 9 although you need to take some or big risk to miss fairway when trying to land the ball from the tee in those flat spots; hole 10. 13 & 16 as far as I remember.
After seeing the last UEL weekly tournaments, Peeble & Masters special Editions (not the Tough It Out) and reading what the now very skilled players comment (at least in my CC) do, I see that people are becoming specially good at estimating the lie almost no matter what speed the threads move sideways, although all of them avoid to have down hill lies anyways...lol.
I guess those top UEL players have become simply so good around the green that it is easier for them to save par (if they miss the green) than the rest of us....and yes they putt awesomely great ; )))
UEL is the game!!!