Quote - ...Did the textures "take" - appear on the figure?....

Actually, they did... the figure did change colour when I loaded 3D-Celebrity's Mandy MATs... and in the mat room, the ImageMap node references for the top set of body areas are all for those MAT files. Then, there is a list of body areas under that where the ImageMap node references are all to the original TY2 body areas.
You know how when let's say you have V4 selected but you are trying to load a dress MAT file from a pz2... and how the material zones are just added to V4 without warning. At least in the mat room, it warns you - I really wish it did in the pose room too, which would save me having to bring the file up in PFE to clean that up. I suspect that is what happened in this case: just added the material zones, but since the OBJ file has been remapped, her skin suddenly had colour, where before she'd just been grey.

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks