Even if it is the color setting for skin (which is not always "pink/flesh" for everyone), the colors would be consistant for every player. Any differences between what you see and what I see would then have to be attributed to color settings somewhere on your computer. Whether it is in the game's graphic settings, your number of colors on the desktop, or your hardware. Otherwise, everyone would see the same the exact same color. I have yet to see anyone look "green" in my game except for half-orcs that I deliberately set the skin color to a green shade.
Some of our NPCs have a more bronze coloring (representing darker skin or very tanned). Rivian should be very light colored being a moon elf. Some of the other elves are probably also done this way, I can't remember now. Also, some of the CRE files were actually made in
IWD and then ported over to
BG. So unless the problem comes from there...