insane 10/10 modi don't think AR10 is much of a problem (or i didn't personally have the issue you're mentioning), maybe it's just you? regardless i think lowering the AR to 9.6 would make a few parts worse, iirc anything below AR10 messes up the taiko stack near the end. more importantly, i don't think the 320bpm back and forth jump part would play well for most people on a lower AR. not at home so i can't link timestamps but you probably know what i'm talking about
While i personally like this map otherwise, there is something i noticed while playing and would like to mention.
When playing maps with high slider velocity and sudden hard-to-read jumps such as 01:42:243 (4) - A player requires time to read such sliders and jumps before actually clicking them. This combined with the map's AR10 makes high velocity sliders and jumps like this close to unplayable excluding players with beyond incredible reaction and reading skills (Which i would say are around 5 of.)
An example of a map similar to this is Hollow Wings' Halozy - Kikoku Doukoku Jigokuraku. This map features the same type of elements as the Sweet Surrender difficulty of CANDYYYLAND. How Hollow Wings' manages to handle reading objects for this map is using an approach rate lower than what the map would otherwise supposed to have, to give the player time to read these objects and patterns beforehand, making them entirely playable.
What i suggest for CANDYYYLAND's Sweet Surrender difficulty is the same. The AR should be lower so that the player could have more time reading the difficult sliders and jumps, making the map more playable and easier to read. I personally suggest AR9.6, but that would be up to the mapper to decide.