First of all I'd like to remark on the coincidentally close your green background is to the one I use, yours is #029c00 while I use #00ae00 
Anyway, your sheets look pretty good, I can't really see much to change. If there was something legitimately wrong with them then they wouldn't have been accepted.
The only thing I'd like to suggest is restricting icons to things that are actually in the sheet. I don't think it's a strict requirement, but I like to try do that with my own icons so that I don't accidentally mislead people in terms of the contents of the sheet. For example with the "Gallery People" sheet I would have it just be made up of a couple of the sprites of gallery people. I mean I guess it's fairly intuitive from the name that the sheet only include the character sprites, but the icon could still make people think that it also includes the actual building sprites/tiles shown in the icon.
It's not a huge thing though, so if you can't be bothered to change it that's fine. Otherwise they look great! Unfortunately I don't play Ib so I can't suggest anything about which areas to rip next, sorry!
(By the way, just out of pure interest, could you maybe post some details about the decryption? As I said I don't even play this but I'm just a huge nerd for game hacking)
Anyway, your sheets look pretty good, I can't really see much to change. If there was something legitimately wrong with them then they wouldn't have been accepted.
The only thing I'd like to suggest is restricting icons to things that are actually in the sheet. I don't think it's a strict requirement, but I like to try do that with my own icons so that I don't accidentally mislead people in terms of the contents of the sheet. For example with the "Gallery People" sheet I would have it just be made up of a couple of the sprites of gallery people. I mean I guess it's fairly intuitive from the name that the sheet only include the character sprites, but the icon could still make people think that it also includes the actual building sprites/tiles shown in the icon.
It's not a huge thing though, so if you can't be bothered to change it that's fine. Otherwise they look great! Unfortunately I don't play Ib so I can't suggest anything about which areas to rip next, sorry!
(By the way, just out of pure interest, could you maybe post some details about the decryption? As I said I don't even play this but I'm just a huge nerd for game hacking
)