00:52:572 (1) - Spinner should end at 00:56:253 or 00:56:526 if you reaaaaally wanna extend it
The usage of normal-hitnormal sounds very off to me, and it doesn't sound like it represents any specific musical layer of any sort, think about removing it or following beats such as 00:26:739 - 00:28:375 - 00:30:012 - 00:31:648 - etc, it sounds alot more fitting and gives the hitsounds extra atmosphere as the song also does create a different type of atmosphere with the added bass.
You need to make or ask someone to make hitsounds for you that both compliment the song and give feedback to players.
I would change the source to "UNDERTALE" in capitals since that is what is used in the official game title.
Timing should be in a 3/4 time signature. It's currently in 4/4. You can change this in the Timing Setup Panel.
in my opinion i think the source should be UNDERTALE instead just the cap at the beginning, i mean when you google undertale it show the website labeling it in all caps
Toby Fox -> toby fox
he has small letters in Undertale soundtrack
also you don't need 'toby fox undertale' in tags because you have it in other fields
metadata source for you: https://tobyfox.bandcamp.com/track/fallen-down-2