It's really difficult to understand how Sony have managed to code this in such a convoluted manner. The fact that fully embedded fonts
do work in the normal way implies that the epub font-rendering mechanism isn't completely messed up.
With many epubs, to change default font ought to be as simple as adding the 4 appropriate @font-face statements to css. Presumably Sony know where the 4 Amasis font files are stored in internal memory. It's a mystery
@Kolenka, Can your better technical know-how of the inner workings shed any light on why the other old @font-face method no longer works?