I've already JB'd by Kindle Paperwhite 10th Gen on 5.14.2 using the WatchThis method, back in May. My 100% sole reason to jailbreak was for custom screensavers, which I've got running grand.

But during the WatchThis jb, something happened with my Goodreads integration, meaning I can no longer update my reading progress with the share > Goodreads option. It's a small feature, I know, and I'm likely one of like 8 people that use it. But I like it, and I'm used to it.

So, my question is, since my PW is already jailbroken, can I downgrade the firmware with the goal of using a fresh jailbreak meant for an older firmware, so that the Goodreads integration still works?

Or is that a silly / unfeasible plan? Or is there a fix for the goodreads thingy? Or a KUAL for Goodreads ( or even Storygraph, so I can de-amazon my Kindle as much as I can )?

Any help or advice would be much appreciated!
This vaguely rings a bell, but I don't remember if a workable solution was ever reached. You might want to go digging in the original WatchThis thread?

(For the GoodReads thing, I mean. A downgrade is doable, but should not be done lightly. IIRC there's a somewhat recent thread on that for current devices... somewhere ;o)).
Here:
https://www.mobileread.com/forums/sh...d.php?t=347165

And I think a re-jailbreak is probably not needed, but reinstall of packages is.
on jailbroken pw4 it's possible to use the "diags firmware" to downgrage to any version of firmware and you can try to use it to downgrade to a jailbrokable (is that the correct word?) version and do the jailbreak use the old method instead of the WatchThis method
be aware that I 've only done this once downgrading from 5.13.6 to 5.12.4, and I don 't know what will happen if on newer version ,so be careful.
I was wondering what happens if one puts an older fw in the root and restarts the device? It simply ignores and removes it?
Yup, the updater throws an error and reboots.