@eishiya. Sorry, I didn't understand. I thought you wanted me to dither the parts in the background so I was confused because I actually tried and it didn't work.
@Vinik. The thing is I have already used this set of colors for everything else. But if I have to I'm open to adding a few colors. I will try making it a shade brighter in a few minutes and see how it looks.
I used the original pallete and changed the colors of many tiles trying to make it as close as possible to the blended image. I think I will keep this one. (Also I made some edits to some ground tiles and other things).