the Rhino 7 error should be fixed in the next Rhino WIP (see here).
About the ngons, I guess the problems comes from the fact that in Rhino, NGons are not actual mesh faces, but groupings of these mesh faces. So, your mesh has still the same amount of faces (either quads or triangles), but some of them are merged at display to show faces with more than 4 edges. Problem is that most Gh components working with meshes operate at the face level, and by changing the faces structure, they delete the NGons structure attached to them.
I believe the best way to address this is to avoid using Gh components and do everything via scripting. I will see if I have a bit of time and try to see if I can work something out. I let you know in case 
And besides all this, super cool images!!! Are you looking to fabricate these shapes at some point?