It's been a few days since her last "accident", and I can categorically say that cotronella DOES NOT HELP AT ALL.
I'd wiped it on the wall where she sprayed, all over the floor, and even left the soaked citronella cloth in the middle of the patch.
And she wee'd on the cloth!! :-)
I have a suspicion that she likes her litter tray to be especially clean and clear, so I'm trying to be more fastidious about scoping her litter tray, and at least it hasn't happened for a while, but it's hard to be completely scientific and consistent with a problem that only happens once a week or so...
13 hours ago