If I gave you my discord could you help me further?
Hey I gotta ask though, how are your walls defined? Do you save the connection points that make up the wall? if so you just gotta do what the other guy said with triangulation.
I just have points like 
(Points in blue)
A yes in that case a simple triangulation algorithm would work if they’re all in the same plane.
You need to use a lot of math to calculate where to put stuff and yada yada yada