@jglerner: In your case, that's most likely normal, the first few versions weren't stopped properly/started too early to be uninstalled without a full Kindle restart
. That's not the case anymore
(Or at least it shouldn't, and it seems to work on my end). (If by 'unsuccessful' you mean that the uninstall update process was successful, but the fonts were still in use ^^).
And I'll say this again: You don't have to uninstall the hacks when doing an upgrade, the install script handles everything (removing what needs to be removed, updating what needs to be updated, and keeping your custom content intact). And if you want/need to uninstall them, you can use the uninstall from the latest version. (In fact, I'd go so far as to say *always* use the uninstall from the latest version, in order to make sure you get all the latest bug fixes).