00:31:591 - through 00:37:591 -
and
01:50:341 - through 01:55:591 -
I think the intensity of these section is too similar to the oni difficulty. The only major difference I see between the two is color changes. You could delete the notes at 00:33:559 - 00:36:559 - 01:51:559 - 01:54:559 - to better differentiate the difficulties and improve the spread.
This suggestion will represent every other piano(?) sound with a 1/4th triplet
00:55:591 - through 01:07:216 - This section is 31/1 long which goes too long without having the recommended 3/2 or 3 consecutive 1/1 rest breaks as stated by the ranking criteria guideline:
"At least 1 rest moment that is 3/2 or longer should be inserted after 16/1 to 20/1 of continuous mapping. Using at least 3 consecutive rest moments that are 1/1 is an acceptable substitute if either the pace of the music makes rest moments counter-intuitive or if the continuously mapped part is overall more forgiving to the player."
My recommended solution is to delete the notes at 00:58:778 - and 01:04:778 - , this will give a 3/2 rest moment to the player. Also will place more emphasis on the held piano note.