i spent some time trying to understand why the roof shape looked that strange to me.

i thought that from a side angle it would look like (1), but that's a really particular shape, nice but not easily readable imho... and i also thought that making that like (2) could fix the problem but would distort your concept. then, searching for totoro's house i found that its shape is quite like (3). i know your house isn't supposed to be totoro's house, and admit fixing it in any other way is too difficult for me, but i wanted to show you what i'd do if i were you. sorry for the crappy edit, but i tried XD
i agree with huzba and also suggest to remove one of the 2 highlights (yellow and pale green) because 1 of them is useless: by now they seem to be just 1 color, they're too similar... you may also increase the contrast between them.
by the way, it's honestly nice, and with some little changes in the palette it would turn out pretty cute for me.