This page in the Admins group has the very best information for figuring out permissions to apply to a role:
Canvas Permission Updates
The Canvas Course Role Permissions and Canvas Account Role Permissions documents, linked from there, are especially helpful. They will help you assess the needs you mentioned (needs to view all types of submissions, can't grade rubrics) in relation to specific features which interact with Canvas permissions. It's worth reviewing the log of changes to permissions on that page to see whether recent changes impact your plans.
If the individual works across several courses and shouldn't be listed in People as being in the course, you'll want to create a new account-level role- either instance-wide or just within a subaccount. (The same role can also have varied permissions within different sub-accounts.) Otherwise, if there will be different individuals at different times needing this facilitator access, registered with specific courses, then a course-level role may make more sense.
I've always found it best to use a "sandbox" course for testing any new permissions or roles. Make one change at a time; wait a few minutes for the change to take effect; and, finally, confirm whether the change did what you expected.
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