Thanks for making the effort to write that down. It’s a very useful way to test a surface.
It’s essentially the way DevLoft works to find where to put rulings.
There are functions used in that process to evaluate a ruling between curves and return the amount of twist across the surface. That is very scale dependent - It measures the rotation required to make the tangent at one edge match the tangent at the other edge without considering how far apart the ends of the ruling are.
I mention that because it would be easy to expose that functionality so that you wouldn’t have to do the line manipulation.
It would also be pretty easy to script something that would do the same thing.
If that would help and if we can find a definition of how it should work, I’d be happy to help with that.
Lowell