Kindle Touch (and PW1) doesn't even need this, you just copy over the old firmware bin and initiate the install.
PW1 if on firmware 5.6.1.1 needs to be "tricked" by force rebooting it (by holding the power button for 15-20s)
without ejecting/unmounting from computer (otherwise Kindle OS will just delete the bin and IIRC Kindle Touch doesn't even need that type of "workaround".
Now, I have one dilemma for Kindle Touch: I can't recall if that device's firmware images had complete rootfs partition image? Or it still used "patching files" approach like Kindle 3 and Kindle 4 did?
If those installers aren't like the ones used since PW1 then your choice for downgrading will probably be using KUBRICK:
https://www.mobileread.com/forums/sh...d.php?t=206064
If you manage to find computer old enough to boot that live CD