O.k. I see the point that there are good reasons not to change numbers carelessly.
I assume, the same applies to color changes. There are some parts, where the color designation differs between Lego and Rebrickable. For instance Part 76537 (Shock absorber) has color designation yellow on Rebrickable (and Bricklink) and black on Lego. A fact that confused me, when starting my local database and some parts appeared twice. Particularly all EV3 Motors and sensors I owned both in Light bluish gray and White, which would have made me happy, if it were true ;-).
But for the same reason as you explained above, it's propably better, not to change color designations. And in most cases where rebrickable colors differ from Lego they are at least in sync with Bricklink.