I have noticed long ago that when I put font files from my typeface library to my Kobo, I usually get terrible results, only few of them work really well, some more work somewhat blurry, rest are terrible.
After years of using them like this and sticking to some nice ones that work well, I thought something I should have thought of the first time I got my hands on an eInk device: What if their pixel alignment are different? Then of course my typefaces wouldn't work as ACCESS and RMSDK read hinting instructions (I don't know about Kindle at all). Those instructions are prepared for LCD and LED screens after all.
So, I checked the screen; it appears it is way more than simply being different, it is completely weird:
https://www.mobileread.com/forums/sho...56&postcount=3
It is the same with newer models too.
Learning this, I told FontForge to render font files with old style kerning (for Kobo's ACCESS) and to discard hinting instructions. All the typefaces that seemed so terrible are as beautiful as they should be now.
I think most of you would already know this, but there might be some slow people like me who haven't noticed yet, so I thought I should tell you.