Another fun complication with this is that ttf, otf, and woff all have a limit of 2^16 glyphs. Which isn't enough to include separate glyphs for all characters

Another fun complication with this is that ttf, otf, and woff all have a limit of 2^16 glyphs. Which isn't enough to include separate glyphs for all characters in all three locales, especially if you include ligatures. This is why some fonts, such as Noto have separate font files for Chinese, Japanes, and Korean. It can also be problematic if you want to include japanese and chinese ideographs in the same document.