Answer
The retry count is stored per message on the ADDRESS_LABEL table (retried_count column, keyed by application_message_id) — querying it directly by the message's ID gets you the figure for a report. The broader message record and body live on the paired APPLICATION_MESSAGE/MESSAGE_QUEUE and MESSAGE_BODY tables respectively, if you need more than just the retry count. Where you don't already know the right table/column for something shown on screen, the browser-based Web Dev Tools' server trace view is the modern way to capture the actual SQL IFS runs to populate a given screen, which is how this kind of mapping gets discovered in the first place.