Unfortunately there is no way to load custom texture nodes into Toolbag from a substance file currently, as far as I know. Right now we read a variety of standard nodes like albedo, normal, roughness, etc. If you have an additional input that isn't a standard substance node you'll have to export that as a separate texture…
So I just started working with Substance Designer, pretty basic and nooby stuff. I was using a edge wear filter from SD to reveal a shinier metal underneath. Exposed some parameters easily, but now I can't reuse the substance with a different mesh, because of the bitmaps I imported directly into the graph in SD, bitmaps…