Texture mapping is baked into mesh UV0 by the exporter (FGeometryChunk..ctor → FConstructionGeometry.ComputePlanarUV / ComputeCylindricalUV / ComputeSphericalUV), not carried as material parameters. Each of the five SolidWorks mapping types is wrong in a different way, and one of them destroys triangles. Separately, and independent of mapping: appearance colours are shipped to Datasmith as if they were already linear (below, E1) — mid-grey arrives 2.33× too bright and saturation drops ~40%. Reference this github repo for in-depth analysis and a patch. GitHub - bdm310/solidworks-datasmith-fixer · GitHub
I’ve submitted a bug report via the Twinmotion contact form, don’t know if that’ll actually go anywhere. Figured I’d also post here so it’s visible and searchable.