Blue sphere difficulty screen editable?

How do I edit the blue sphere difficulty screen sprites? I want to create updated sprites for the characters on screen, but I don’t know how to since I didn’t see these sprites in the data/doc folder, and I don’t know of any mods that change these sprites, except mania Eggman which only changes robotnik’s sprite. Here’s the sprites I want to change: info.sonicretro.org/images/0/00/Bluesphere.png
Thank you!