This would be a cool function but I have no idea how hard it would be to implement. Also, if adding tint to vision is as wonky as I've experienced then I would dread the kinds of issues this could cause. In my cast, any time a situation arises where something important on the map depends on color, I make the item monochrome (or invisible) until it comes into the line of sight of a PC with carrying a light, at which time I describe it in either a chat whisper or a private voice channel.