A very intersting question now comes to my mind:
The standard procedure of jailbreaking is:
1) Register your Kindle to make sure you get all menu options.
2) Do a factory reset. (And keep in mind that this must NEVER EVER be done again!!)
3) Install the initial factory test firmware.
4) ... all the other steps for jailbreaking ...
Does the procedure in 2)
not change the registration state then?

I always thought it is a pure local thing and is also reset by doing a "factory reset", which I supposed removing securely all and any personalizations...
BTW: I never plan to do a rsgistration with Amazon. Is is as well as the "factory reset" a definitive no-no for me. I intent to use the Kindle as an offline ebook reader only; I even don't have an Amazon account to register with. All my documents are from other sources and without any DRM. So there also will never be a change in the "registration state". And this could also explain why I don't have any problems with the "document style" launching method of KUAL and CoolReader and KindCalc (the *.azw2 files in the /documents folder) even with 8th generation Kindles running fw 5.8.7.0.1 ...
Gesendet von meinem Google Pixel mit Yabba-Dabba-Talk.