Hah! I think I finally understand! Thank you 
again for sticking with me!
So, my understanding of the extension was mostly wrong. It doesn’t import anything from SketchUp other than what’s already in the model’s material list. I think you may have already told me that, but I misunderstood and thought it meant all of SketchUp’s native materials.
As for the shortcut to add a material, if I understand you correctly, you’re saying this is the same as adding my own custom materials through SketchUp. I can upload it through SketchUp or I can add it through the extension.
Phew! Now that I get it, I can make proper use of it! 
