How to reverse damage done by nail polish remover without acetone to a laptop keyboard?
The solvent appears not only to have removed paint on the keys but also to have caused solvent crazing in the plastic itself. Regrettably, there is probably not much that can be done to actually remove the crazing, which may have penetrated too deeply to remove by buffing, but you might be able to hide it with a substance such as an oil that has the same index of refraction as the plastic.

If the appearance is unacceptable, you might replace the keyboard, use a plug-in keyboard, or get a keyboard cover, such as the Kuzy Russian Keyboard Cover, specific to the Mac Pro. Individual key stickers would probably not adhere well.