At this moment, your oni diff, is an inner oni diff. (this also means that you are missing oni diff)
Now let's understand a little bit about the oni and inner oni restrictions:
(some terminology. (N)plets, this is number of notes in 1/4 row, for example on oni is 01:21:518 7plets)
Oni diff:
Guided by RC taiko, we should know that oni diff generally uses a maximum of 5 plets (you can use 7 and 9 plets, but these are rare cases + special conditions and it is easier for new mappers to remember 5 plets). Also, even if you map 7 or 9 plets, they must be followed by rest moment. 7+ plets for oni should have simple colors so that new players can play them (e.g. kkddkkd, kkkkkkddddk)
Inner oni:
There are no restrictions as such, but the goal is to highlight song as best as possible with denser patterns and frequent color changes. You shouldn't miss the sounds you follow, and even more, inner oni welcomes overmapping, but it takes experience to get the overmapping right and good
These are the main points that your oni is currently violating and is in fact an inner oni
(If you are interested in more detailed points related to the limitation of oni diff, and other diffs in general, you can read about it in Taiko RC. https://osu.ppy.sh/wiki/en/Ranking_criteria/osu%21taiko)
At this moment I would suggest making this dff more complex, maping all the rhythm you are following, and since this song supports changing SV, use that as well (just don't go overboard, simple SV changes will be enough)
Also about oni diff, just map diff basically with restrictions I wrote you above (or as a last resort, you can ask someone for GD)
You need to change volume depending on part use Inherited Points (Green line), It also helps to highlight the quiet part from the active part.
Tip, I usually use this pattern: 70% for break, 80% for active part, 90% for the kiai