If I understood it correctly, stealth works like the following at the moment:
If a creature you are hiding from does not have darkvision, it will not see you at all when you are heavily obscured, and you will have to make a stealth check when only lightly obscured.
If a creature you are hiding from has darkvision, it will always see you when you are lightly obscured, and you will have to make a stealth check when you are heavily obscured.
Problem is, unless you want to click on each creature and check if they have darkvision, you won't know if you have a chance at hiding in a lightly obscured area, or if you will be detected immediately. Therefore I propose that creatures with darkvision get vision cones in a different colour, maybe purple or something. This way we can immediately tell if it is possible at all to hide from that creature in a lightly obscured area, or not.