I believe the piano is a more emotionally evocative instrument in regards to a song. It might not hold the strictest significance in terms of volume, but the piano is definitely an important instrument within the outlined sections. Following the vocals does not capture the same emotion that the piano does, and I feel as if the map is ever so slightly more hollow upon application of following the vocals. The resonance in the song with the player isn't evoked as instrumentally as it could be, so I will take it upon myself not to change this pattern as I firmly believe it captures the harmony of the song.
The piano itself mostly blends in with the vocals on that part, the sliders I put are to represent the less audible piano notes so they're not clickable, they do represent vocals but I did not count them in the foreground.
02:12:126 - 02:44:126 spacing emphasis in this part is kinda broken sometimes since you have stuff like 02:12:876 (2,3) - , 02:14:876 (4,1) - , 02:20:876 (2,3) - etc. which feel underspaced compared to actual intensity of the sounds in the song
this can be also applied to 03:20:126 - 03:50:126 to a less exten since stuff like 03:28:876 (2,3) - , 03:30:626 (3,4,5) - can definitely be spaced out more
Your use of volumes needs some work, considering the highest % of volume you've used in the entire map is just 50%. I'd suggest in general to buff the main kiais to 70%, also buff all other sections accordingly. 30% in the non vocalised slow parts is ok, but you should buff parts like 01:22:126 to 50-55%. Also you could bump up the volumes on the small kiais you've used on some sliders to 5% more than what the rest of the section they're on is, it would be a nice touch