Unofficial Skyrim Special Edition Patch

I did some testing/troubleshooting involving mounting and dismounting swimming horse.
Here are my conclusions:

1. When entering the water on horseback, horse swimming animations will play correctly. (IsSwimming console command returns 1 on the HorseRef and 0 on PlayerRef)
2. Dismounting this horse will enable the player correctly dismount. The horse and player now both have correct swimming animations. (IsSwimming console command returns 1 on the HorseRef and 1 on PlayerRef)
3. Remounting the swimming horse will now cause issues: The horse will now use walking animations instead of swimming ones. (IsSwimming console command returns 1 on the HorseRef and 1 on PlayerRef)
4. Dismounting the horse in this state, will make the player fall down the water, like he was walking on land. After a brief moment, the game will catch catch and make the player no longer "fall". (IsSwimming console command returns 1 on the HorseRef and 1 on PlayerRef)

Additional information:

This issue has been reported on the UESP page for horses: https://en.uesp.net/wiki/Skyrim:Horses down at the "Bugs" section: "When you mount a swimming horse, the horse will move as if it is running on land. This effect lasts until you ride the horse back onto a surface it can walk on normally." -> I can confirm that this is the case. If you walk back on land, the swimming animations will replay upon re-entering the water, HOWEVER, if you then dismount the horse, the "falling through water" described in step 4 will still be present.

I adressed this bug in my mod Andrealphus' Exploit Fixes: https://www.nexusmods.com/skyrimspecialedition/mods/46753 (Horse Exploits Fixed section) in which I used a scripted workaround, which is more of a bandaid. To properly fix this, I would assume editing idle animation records and correcting the behavior graph is probably needed.