@bosn
I'm not sure if you were talking to me or pianohombre but I have found most of my notes
for the mmx v1.1 data structure for the sprites that I will hopefully have posted within
a few days so everyone will have access to it.
The problem is trying to find what values control what. I'm not even sure which variable controls the starting point for the graphics table in the editor (you need an address obviously which is like searching for a needle in a haystack.) But that's not all that's required. Several variables control graphics disassembly and assembly. It may use the same compression algorithm as MMX1-3, but I'm not sure. So I may have to use like an exception clause for RNF to run a separate function/class that handles this game's compression, assembly, etc. I have the addresses for the graphics pointer table I was able to find by a disassembly program, but I think there's like an offset value or something (another unknown that has be included in the function).
I found the majority of my notes for how the data works which I will post soon but from what
you have said it seems like your biggest problem is understanding how the snes hardware works.
If you understand the hardware you should(or seems like you should) be able to find out how
the data works. I would like to show you how to figure out how the data works instead of just
showing you how the data works.
To be able to figure out and understand the sprite data own your own you really need to know how the snes:
1: cgram registers work
2: oamram registers work
3: vram registers work
4: 65c816 assembly language works
Knowing how these snes registers work will give you the ability to trace the assembly code
backwards to the location of the data. If you know these 4 things the data wont be like
"searching for a needle in a haystack" it would be more like hunting your prey.

If there is any of the 4 things listed above that you don't fully understand just let me know which ones
and I'll walk you through each one in search of the mmx data that you need to understand to accomplish your
goals with the mmx editor.
As far as the c++ I'm probably not going to be much help with that part but I can do a little bit.
I mostly use QT for my c++ and I do have some stuff written for mmx to view the levels and sprite
data but nothing I have available yet to edit the levels and data. It will probable be awhile before
I'll be ready to finish my QT c++ programs for mmx but it is something that I would like to finish
eventually.