Having been through and calculated all activities >30km, I have lost just one key tile in my cluster, which takes my max square back down to 17 - another one of those mildly annoying ones that I could easily have ticked off on one of my recent rides if I'd known about it. Pah!
Not going to bother checking the 1600+ sub-30km rides/runs. There will be an awful lot of repeats among them - around 200 of them will be my local parkrun, and then there's the route I used back when I was running 2-3 lunchtimes a week... Using the filters and scanning over the map, it doesn't look like there are any controversial tiles left, so that'll do.