So, if you turn force unicode font on, and fill up the page of a book, save the book and then turn force unicode font off, some of the characters will dissapear. They will reappear when force unicode font is turned on. This is because the unicode font has smaller characters, so all of the characters are able to render in the page. This can cause issues, for example if a player with unicode font on makes a book and gives it to a player with unicode font off, that player will have to turn it on in order to read the whole page. Basically, for whatever reason, you can put more characters in a written book with unicode font on than off.