Your window geometry is probably not well aligned with the wall and that’s why this is not working for you.
Curved surfaces do accept windows as you can see in the image below. Though is not based on a surface but rather on a percentage of the wall, but the principle is clear.
Yes. I know i’m doing something differently, but just to prove that curves windows can be possible.
I bet the problem here is that the geometries are not fitting each other. See image below. When you zoom in you see gaps between them. and they are causing the window not being recognized in HB.
I tried to increase the tolerance but no success with that.