@Bismar: The usual way, the hacks don't change a thing.
@montalex: That looks like what happens after an update ran with usbnetwork enabled, so, unless you yourself are using usbnet, I'd blame this on Duokan messing around with the USB gadget modules

. [This specific issue has been somewhat fixed in usbnet .29.N, BTW].
@Dusty Star: Nope, the credits file is just, well, to credit the authors of the fonts in question in the package itself, you don't need to put it on your Kindle

.
Did you use one of the new FT override option to make it work, or did it just suddenly work with this update?