Tools and colors limits when creating CG backgrounds

I have been playing with integrating CG background image using FEbuilder, but I really dislike the palettes that the converter automatically creates. It creates really weird and obvious 4 quadrants of colors that looks stupid because of the way the TSA rule works.

This is prompting me to feel like I need to manually just create my own image to import (so I can specify the palettes of my choosing), but I am worried about the tedious nature and easibility to make a mistake. One pixel in the wrong place will cause FEbuilder to have a meltdown. Is there any tool that you’d recommend for creating CG backgrounds that can easily be read by FEbuilder?

What are the thresholds of what is considered okay to load into FEbuilder?

  1. I was testing it out with 13 palettes of 16 colors as that seemed to be the format that worked from the Decrease Color Tool. This did not work.
  2. I tested out 10 palettes of 16 colors and this also did not work.
  3. Finally I tested out 8, which was able to successfully load into FEbuilder. Is this the maximum number of palettes I can use in creating a CG. 8 palettes of 16 colors? Is there any way to increase this?