Thank you for your swift replies!
I bricked my Kindle the last time before I even started applying font / screensaver hacks, so I wanted to be more certain this time how I could undo the hacks.
There are a lot of hacking tutorials but not enough information on how to backup/restore them I think.
I'm debating whether it's worth the hassle to jailbreak. If I do eventually try to change my CJK fonts maybe I can report back.