Solved
Seasonal Lot Marker Errors
I created a world called Alryne Valley, and apparently, the roads in the center of town overlap the 64x64 lot just enough to cause seasonal lot marker errors when placing the festival grounds, as par...
I took the 60x60 festival lot I created, which worked without errors on a 60x60 lot in that space, and placed it on the existing 64x64 lot. When I saved the game and reloaded it, the errors resumed. I could have saved a lot of time if I had tried this first!
So, it is official. The overlap itself is the cause of the errors. There is only one resolution for this issue: to replace the 64x64 lot with something smaller that fits in the space.
At least I know for certain that there is no other workaround. And I won't have to ask the wonderful people at NRaas to decipher my error files.
