CalDAV calendars are not modifyable when added from gnome-calendar UI
Adding a CalDAV calendar from the gnome-calendar UI (calendars → add... → from the web) leads to having a calendar that is non modifyable. Calendar events are read-only and adding a new event does not allow to use the calendars configured.
There is no reason not to allow them to be modified, and gnome-calendar already supports backend with modifyable WebDAV calendars. Also, when adding a WebDAV calendar through Evolution leads to having a modifyable calendar in gnome-calendar.
The problem from using Evolution to add calendars is that this is not possible when using gnome-calendar as a Flatpak application on a system (like Fedora Silverblue) where Evolution is not available and not installable (and adding calendars in flatpak evolution does not mirror the calendar configuration in flatpak gnome-calendar).
As an alternative, is there a command-line workaround, or text configuration that can be changes to configure CalDAV calendars read-write?