So I've used the importer on one UE4 level and it works great, but when I use it on a second it ignores the mat files it's generated and replaced everything with "WorldGridMaterials".
This is the level in question (UE4 4.17):
https://drive.google.com/file/d/0BzY0iE-8FLJeQ2xWLWw3RTQ3OGc/view
Alternatively, how would I interpret the mat files if I assigned materials manually?
Diffuse=T_Metal_Aluminum_D
Normal=T_Metal_Gold_N
Other[0]=T_MacroVariation
Other[1]=Tex_0724_4_NRM
Other[2]=Tex_0795_0
First 2 seem obvious but it's Other[2] that's actually the main diffuse map.