Hello Gildaniel,
I think that your problem can be solved if your CAD-software has export option like 'Export Edges' in Sketcup Make 2017 I have used here.
Usually I dont't use this option but now it is necessary (picture below)
Below is part of SH3D:s 3D view: on left 3 pillars exported without Export Edges, on the right same pillars exported with that option.
And in last picture can be seen Furniture Material when rightmost 3 pillars are selected. Now there is edge color available as needed.
I hope this help or at least show some possibilies to solve your problem.
Seppo
