Contacts that were imported into Contacts Journal will keep all the information in sync with the Contacts app, so you can update phones, emails, notes etc without having to make the changes in two places.
You can create new contacts in Contacts Journal, and they will be added into the Contacts app as well (though if you create Private Contacts, those are saved only inside Contacts Journal)
If you create new contacts in the Contacts app, they don’t automatically get imported into Contacts Journal. When we detect new contacts in the Contacts app, we pop up an alert asking you if you want to import them into Contacts Journal. You can then see a list of these new contacts and import them if you wish.