Everything seems to work OK with the current KindleImport. Now I'll have to update the plugin to remove the dependencies for the framework version of the compatibility_utils. Since we're not supporting python 2 anymore, the plugin code itself shouldn't really have any need for the compatibility stuff. The core kindleunpack module included with the plugin is pretty-much self-contained.
I'm in the middle of an overhaul of the TagMechanic plugin right now anyway. Moving from tkinter to pyqt. Dropping support for Python2 was something I'd already factored into that.