Low-Level: How to copy appdata from android 4 kitkat to android 6 marshmellow
GiantTree got this thing working. With his comment I found 
https://forum.xda-developers.com/showpost.php?s=08f8d78aabe88fb570ec1e59a37e71a8&amp;p=67319237&amp;postcount=3

Which does the trick. So you need to fix user, group, Unix rights and SELinux Security Context. Thanks for this quick reply!