mfa_reader should read four active title and artist pairs through collection_analysis and have no reason to read collections. answer.sql is assistant-written. Predict its visible row count, run it, then revoke the accidental table access and leave the role with the view-only permission.
Expected if it were right: 4 rows. The shipped file grants the role the base table and returns 5 rows, including the soft-deleted Hidden Study. The defect is the object named in the GRANT.