Something weird is definitely going on.  The main material is apparently the cuplrit and I agree it does LOOK like the trans map is being applied as a texture, but there's no such connection evident anywhere I can find in the GUI.  To further confuse me if I nuke the main material's transparency node the material preview is super dark for that material, but not any of the others.  Even though they all have the same main mat'l settings and all have their Diffuse and Specular colours connected to simple image nodes with all the same text map and the base diffuse and specular colours are all white.