Clarify the model. Give elaborate definition of what exactly each entity is expected to be. Give clear explanation and examples how to cope with many possible alternative situations that exist in practice. There may be many possible roles that agents can have: authority, owner, creator, rightsholder, publisher, contributor, custodian, etc. There may be many ways that datasets and their metadata can be serialized: datastore, dataserie, dataset, datafile, dataportal, datacatalogue, etc.
Clarify the model with examples from practical situations.