I'll give my few cents:
White roofs for the houses seem odd, and they aren't very historical. I'd go wither with grey tiles, or thatched roofs, or both.
The green roofs on the castle is ok, I'd prefer grey to make it look more generic, with green it makes me think of Osaka-jo.
The walls looks very un-Japanese, but its probably because you want to mass produce sets.
It'd get rid of the green top on the Tori, a mono-chromanic one would be fine.
Would it be possible to add a bit of dirt to the front house that sticks out? That way it wont look like its floating on water if placed on the edge of land.
But this set is much better than the first previews of this generation