Yup - you did it.
You changed the registration which removes our application keys.
Re-install the 'hotfix' package.
With a customer-use firmware build, you will have to use MrPI.
Since KUAL is not working until you re-install the keys . . . .
You have to trigger MrPI using its main page, search bar, command, enter:
;log mrpi
(the semi-colon is part of the command)
after putting the 'hotfix' package in /mrpackages.
Also be sure to install Python from NiLuJe's snapshots thread.
https://www.mobileread.com/forums/sh...d.php?t=225030
If you intend to use "cover mode", then scroll up to find an archive that contains a fixed file to support all versions of kfx books.