Firmware 3.5.0 Update on "No italics for generic sans-serif font family (fallback font)". See this
post.
The known font issues are still the same for regular epubs.
For kepubs however: this is now totally messed up.
Everything is now displayed in the font that is selected by the user. Applies to both system fonts as user installed fonts. (Generic) font-family are not respected at all.
Only when the font is set to "Default" there is a distinction between font families: serifs are displayed as serif and sans-serif as sans-serif.
It only getting worse and worse.