Are there any lists or such things anywhere that define what each color in the material palette means? I believe I'd come across something like it at some point, but repeated searches using "mat" "material" "color" "palette" "meaning" "definition" and varied combinations thereof yielded nothing.

uh, yeah, the "Index" value in materials.ini for each mat.

Ah. Lovely, thank you.

Glad to help. I'm not actually sure what the convention is with materials but it would definitely be a good idea to pick an index far away from the current vanilla ones in the palette and remap that. You can also change the colour to something more appropriate than pink or black or whatever it is for the materials palette for the colourmap of the images you're editing, as the game only reads the index, not the colour.