@hilbert a little late to the party, but you are right the other variables should not impact your sync. I think the "config name" can be important, if you used special characters it could be problematic, but other than that they all are phone related.If you still have problems with carddav sync, i wrote a script which setup these things with automated sync (systemd instead of cron), take a look here : https://forums.ubports.com/topic/10127/contacts-carddav-automatic-setup-and-sync-through-this-script (hoping you already solved this issue )

Got "generic Cerddav" working too, but for that one there is not any check and feedback when you create your account.