Thanks for your work, JSWolf. I really do like CharisSIL. For me, the line spacing is good.
I installed your modifed font on my Kindle Keyboard and it worked fine on a mobi file but not the KF8- it displayed using the default serif font. I went back to Calibre, converted the mobi to KF8 embedding the font in the process. That worked. Tomorrow, I'll try your latest version. I didn't realize there was a potential problem with the version I used until now.
Anyway, here's a side-by-side of the mobi/KF8 on the KK: