I guess I'll have to wait for it to get fixed. 5.12.2 apparently doesn't have ;log, so I can't install KUAL since
Update_KUALBooklet_hotfix_44a61b6_install.bin fails in the same way.
I actually had this Kindle for years, and it was jailbroken previously, but I decided to nuke everything since I had completely forgotten what I had done to it before. And it's kinda cool to see this new development on an 8 year old device, you are doing God's work here.