Since I don't know how to edit with AF color palettes or code, this only will be done with the GIMP or Inkscape color palette file. You'll have to update everything else that has to do with the color palette. Also, with the new skin tone colors, you'll have to update every human emojis with them. And because of that, you'll have to update the skin tone generator and the emoji builder. (I don't know if you'll have to update the skin tone generator and the emoji builder, but you have to update the human skin tones with mine.)
⚠️Warning⚠️
Since I don't know how to edit with AF color palettes or code, this only will be done with the GIMP or Inkscape color palette file. You'll have to update everything else that has to do with the color palette. Also, with the new skin tone colors, you'll have to update every human emojis with them. And because of that, you'll have to update the skin tone generator and the emoji builder. (I don't know if you'll have to update the skin tone generator and the emoji builder, but you have to update the human skin tones with mine.)