well. first of all, when the rain begins to fall is easier than the other maps in that level, i would suggest putting it in level 0 instead.
i dont have every map on the list so i cant really tell right now about other maps and their location, but there are also a lot of maps that are in a higher difficulty just because they are harder overall but their jumps arent that hard (kokou no sosei, as i showed before) and there are also maps lower because their jumps arent so hard while the map in itself is impossible for certain people.
also some of the higher levels have songs that are way easier than other songs in the same (or lower) level.
matryoshka and kokou no sousei are hard because of their high bpm single tap, but overall they arent that difficult.
no,39 on the other hand, i dont see myself even getting a B on that with nofail on, same with songs that are on even lower levels.