It's quite odd. Here's the latest thing I ran into: I have a large room with lots of rounded walls and straight walls. I was expecting issues with the rounded parts, but now when I draw say a 6-panel straight wall across the room to divide it, I can't apply wall coverings to one or both of the two end pieces of the wall.** It only shows on the 4 middle pieces, or the 4 middle pieces and one of the two ends. I found a fix which was drawing one panel, put the covering on that, and then extend the wall with the arrow keys to get it to go all the way across the room with no drywall showing.
Oh, and when placing a rounded room on grass, there's no way to fully cover up the grass with floor tiles. You get a bit of grass showing through at the curve even if you draw floor tiles on both sides of the rounded wall.
But, if you terrain-paint something on the grass first, and then add floor tiles, the floor tiles will go flush with the rounded wall as expected. No terrain paint shows though.
???
I guess I'd rather have the option to make curved rooms even if it is slightly glitchy here and there?
**Edit: I figured this one out... Walls in rounded rooms seem to have a "sweet spot" partway up the wall where they can be clicked on to apply wall covering. Too high or too low doesn't work.