@scooke yes, you can mix between Cloudron's automation and manual DNS changes. In fact, that's the normal and only mode of operation.
The automation is only adding and removing things that you would have to do normally outside Cloudron. For example, when you install an app, you have to setup A records. When you uninstall an app, you remove the A records. This is all the automation does. If you try to install an app in a location and there is already a DNS entry in your DNS provider, Cloudron will inform you of the same and let you 'overwrite' it or cancel the app installation.
Same goes for email stuff. It sets up things like DKIM/SPF records automatically. These are updated carefully to not collide with existing entries. The MX record is only touch if you enable incoming Cloudron Email. Even in that case, there is a checkbox to not update DNS.