After a few days of struggling, I was finally able to run KUAL & KOReader on my Kindle Touch, but only by keeping the device in airplane mode during the whole jailbreak process (per
this discussion of a different device, might be unrelated) and installing the new
DevCerts after the JailBreak (maybe they should be included in it?). Thank you NiLuJe for making and maintaining these hacks, and everyone else who provides advice & support!