Normally all the fonts in the accesable area are Additional fonts. The basic set ist stored in the ROM.
But I saw that u have the profile feature enabled. I dunno if there is a chance to delete the profile and start with the standard. When u install a new firmware all the extras like profiles are not replaced. So the new firmware loads again the old mess from the user storage, if the profile is messed up.
So best would be a hardreset, save all ur books and files before. then the PB is like Factory default restored. Also if u have DRM Files I think u have to de-authorize the device first, before hardreset.