RBAC Core and Authorization Extension are two different concepts. Unfortunately Delegation Admin Dashboard relies on the older one.
You can of course update a user’s RBAC roles via Management API, with the relevant endpoints being:
and in this way, keeping the roles in Authz extension and RBAC Core for a user in sync (at least according to the role names; they’re of course different role entities)
Of course the question is when to update the roles via Mgmt API call. It’s something that could be handled with either Management API Webhooks or getting the log stream and listen for events to changes in a user profile in the logs, which would then trigger the Mgmt API call to update the user RBAC roles.