The surviving libelli document compliance, not casualties, and no ancient Christian writer or modern historian has reconstructed an aggregate death total for the roughly eighteen months of enforcement; only named individual executions are on record.
What would resolve this A systematic collation of the named martyrologies and surviving correspondence across the persecution's eighteen months, of the kind that could establish a documented floor even without a claim to completeness.
OpenRoman imperial history; early Christian source criticismPersecution of Christians in the Roman Empire (Wikipedia)