I think the intention here is for actor to be a server Actor (or a moderation-team Actor?) and the attributedTo to be a pseudonymizing euphemism for the actual reporting end-user, which is reused across all reports from a given account but can only be de-pseudonymized by the server/moderation team. I checked, and while Actor is a { Link | Object } that has to { dereference to | be } an Actor object, attributedTo is a { Link | Object } that a note in the ontology specifically mentions does not need to be. So I think a URI (which could, perhaps, be dereferenced to the original Actor by another method or endpoint?) would make sense here?