Titanium Backup cannot Backup Accounts
Thanks to the https://github.com/machiav3lli/oandbackupx/ project I found out that the accounts are saved at /data/system_ce/0/accounts_ce.db, at least for me. I then tried, editing this file very careful, but I think there are some dependencies to other things I don't understand yet. Even with the smallest editions my phone got stuck in a bootloop. Also recovering an backup of the file, didn't fix the bootloop. I had to restore a whole nandroid data partition backup.