Wow I specifically googled this topic because I just got Tropical Skyrim and there is no color whatsoever at night in-game for me as well and I am looking for a fix. I just started a new game with this mod and I haven't made it further than Whiterun so I have as yet to check if the problem persists in other locations. I only have a few other mods and I changed the load order to give this mod priority but it didn't help. I will continue to try and find a solution.