Gau dressed in Locke's outfit

I can't remember the term, BUT offsets like D0/67D5 (to find in a hex editor) subtract C0/0000 to get the actual address in the editor.

I seem to recall there was a Hex editor that would display offsets like SNES sees them, but I always used "HxD" and a calculator when D0/ - C0/ doesn't compute.

Windows' calculator is your friend. Personally I like the old XP calculator, but Win10 still has a "Hex" mode (think you have to set it to "programmer" in newer Windows.

But thats how to read that part anyway. Subtract C0/0000 from the address to get the raw address.
D0/ - C0/ = 10/0000
C3/ - C0/ = 03/0000

As for what to do once your there... Yeah you picked a doozy to start editing on. Not sure if there is a proper disassembly on bank D0/. Personally all I have is one with the info I fished up adjusting battle intros for NPC sprites entering battle, then a little bit of a break down on a few battle events. No sort of break down as low as D0/67D5.

In other words, best I can suggest with what I know right now... Look for either a labeled "Bank D0 disassembly" or search for a post with information on how the data is sorted.

The idea is great, the lack of information on D0 just makes it a tuff place to start editing.

EDIT: After some looking, "Battle events" and commands are fairly documented, but that's all D0/9000 and up. Personally, I don't know what the data at /67D5 would be called, other than "Bank D0/" ...
Again, using that "extra" sprite slot as a pre-jump pose is a slick idea. What I don't know is, if a "simple" edit would make any sprite attempting to jump use that extra sprite (which means ANY PC using "jump" would require that extra sprite to not glitch or not. Wouldn't be difficult to write an exception type interrupt that would check for that sprite and only use the other pose for that sprite number... But that would really require knowing how that part of data is used/read.

DON'T give up on the idea, but it'll probably take some digging.