So I forgot to block OTA updates and mistakenly let my PW3 update to latest firmware (5.9.2) after downloading a new book. Thought maybe I had shot myself in the foot, but I followed most of the instructions
mentioned in this section of the thread and was able to reinstall KUAL. Tested KindleLazy and it still works fine on this firmware.
Not sure if this is helpful for anyone, but just an FYI.