We've succesfully customised a korean menu some time ago, so adding hungarian I think it's not so hard. Check this link for more accurate description:
https://www.mobileread.com/forums/sho...2&postcount=10
EDIT:
the menu on the link is grabbed from a 2.0.5 firmware so probably not covering full changes since last firmwares. Anyway is simple enough to pick up an updated one with the help of applications like rsh.app.
Eventually don't worry, it can be done