Thank you 
I just deleted my newer account
I used the occ to copy the files over (had to remember that the copy command is case sensitive and the login mask isn’t in terms of accountname), then i dowloaded and uploaded the Calendars.
Then I tried to connect everything with my old account, seems like i only got this error left Nextcloud 11 seems to break gnome integration (or was it this one? NC12 Authentication issue with Cardav, Caldav and Sogo connector ) hopefully i’ll find a solution in that thread ^^
for now gnome sais “Authentication failed”