f*** really some new python version helped. thanks!
Did with Kindle Version 5.4.*
managed to see the wallpapers perfectly.
checked everything today, updated to latest: 5.8.7 and also logged in my account.
and the unsubscribed the advertisement service.
reinstalled all plugins (they were there but to be sure),
read the complete README file.
now see the amazon stock wallpapers.
*checked the images on the storage, they are there and "correct", were shown on 5.4.
*deleted them, restarted, copied them again and restarted, didnt change anything
*disbaled, enabled the setting for the wallpaper hack, still nowthing shown.
i got now cool amazon wallpapers, and they're not too bad, but i would really like to see my own custom ones, so -> any ideas on that?