My idea is simple.
If all the text in the book look exactly the same I assume its harder for the brain to remember it. I believe you need a little variation to call upon the handwriting recognition wet ware in the brain.
Therefor I think there should exist fonts that outputs variations of the characters without them looking all to different. Just as much variation one would think looks good.
One simple way to solve this could be to store the variation vector images for each character. So that maybe you have 5 variations of A’s and so on.