Hi. I don't normally respond on Serenes but I'm gonna respond to this.
Short answer, I'm probably not fixing it.
Long answer, Yes. I can use the skin tone. As someone who normally uses full palettes when spriting I agree that I would rather have a pure white color, but this was caused by a couple things.
One, is palette limitations. There's a couple portraits that are hitting the 16 color limit without even coming close to to having access to white. Judith and Richter aren't notable for this, but there are other characters we have where I've already had to cut out quite a large number of colors already, and those colors don't use white at all.
Two, is technical limitations. For whatever reason FEditor sees 248,248,248 as transparent no matter what we tried. If I'm going to be forced to use off-white anyways I don't see why I can't use the off-white of pale skin tones.
And three, is relative shading. Basically, due to the fact I'm shading it with grey (or blue in Richter and Paula's cases, again, to save palette space) unless you're closely examining it, or told directly, you shouldn't realize the white is the skin tone. It will look off-white, but won't match the skin. It is a trick of contrast.
Basically, while I get the reasoning, unfortunately as far as I'm concerned it's not really possible. It'd also be a LOT of work to go back and try and fit an extra color into the ~50 portraits I have finished so far, where I'm already pressed for time to finish the ones we need to get the game out. I'll definitely think about it going into future sprites but it's not really a concern, nor something I'm going to go out of my way to accomplish.