Would it be possible to add a bigger variety of fonts please 
?
Any particular fonts you’d be interested in?
Latin Modern that would be excellent. Or latex based fonts. Those are beautiful.
It would be great to have OpenDyslexic for those with dyslexia.
In the same vein: The font choice seems to affect reading mode, but not practice mode. It would be nice if the choice affected those modes and vocabulary lists as well.
I find the standard font (Jost?) too thin and stylized, not really suited for longer reading, and I have to squint at some text in practice sessions on Android. IMHO a boring but legible, less tiring font would be better.
Noto and other Google fonts were engineered specifically for mobile legibility, maybe those would be good candidates. They have lots of glyphs so one set of fonts could cover most languages.