Much better! It looks significantly better with those actual hills. Nice work.
Now... on to the palette. Don't let this be discouraging, but I suggest that you start over completely. 100% start over, like make everything vanilla smw palettes again.
Now, the tricky thing about sunsets is that a gradient is almost necessary for them to actually look like decent sunsets, but since you're using a mixture of these ghost tilesets and stuff, it really doesn't give off a sunset feel. Instead, it kinda just looks like you made the sky orange. So I would start by scrapping the palette, unless you would like to make a gradient, in which case I can point you to a tutorial or just tell you how here. I know you want to make it look like a sunset, but it's really hard to pull that off, and the black background doesn't work with making it look like a sunset because the foreground is colored.
So, now you have your vanilla palettes right? Now, I would stay away from orange and make the sky black with stars added, because I think right now that would make for the best looking BG. In order to do that, disable
for a sec and click
and change the first option to rope 2. Now, you should be able to access stars in whatever gfx you have in your level, and you can make it a nighttime level, which would go well with the ghost tilesets and castle sprites in my opinion. Once the background is night time, make the hills a very dark shade of blue or green, or honestly, you could just keep the blue hills the way they are (it would look better than what they currently look like).
As for the foreground and ghost house tiles on the contraption thingy, make the foreground the regular smw palette but maybe change the green shading in the grass slightly? When in doubt, keep the original smw palette because the original palette usually looks better than a lot of palette combinations, unless they're done well.
As for the rolling contraption, the donut bridges indeed don't look anything like wheels, and it really wouldn't hurt to completely get rid of them. Also, I would keep the ghost house tiles brown, because they look best when brown, they don't really look great while orange.