At the moment it is not possible to define a role for somebody who should only have access to community metrics of all public and
moderated communities. You need to be owner of each community or have the role community administrator that also allows access to e.g. restricted communities.
We need a role that only provides access to the Metrics component of each public and moderated community without granting access to restricted communities.
There are roles available for the global metrics already, but not for community metrics. Please implement this in a future release or let us know how to configure that.