PROGRESS
and does anyone have a clue as to WHY colorshift is affecting certain faces of the model that arent blank.png
Whenever you make objects, make sure that bits with transparent textures (blank.png, black25-75.png, whiteCheck.png, etc) never grouped in the same object as bits which have other colours (gray25-75, red, etc.)
So let's say you have a cube with one side that has blank.png as a texture and the rest is red. If all the mesh bits are within one object, and you paint it blue, the blank bit will turn blue, while the red bits will become purple. But if you separate the blank.png bit from the rest, then if you paint the cube blue, the blank.png face will turn to blue while the rest remains red.