You'll have to bring that up with the PgAudit maintainer. Note, though, that the purpose of PgAudit is not "recreate the database from audit logs"; it's "what Auditors care about". In my experience, auditors do not care about COMMIT and ROLLBACK statements.
In my experience auditors care a lot about a statement that happened versus a statement that didn't happen.
The SELECT statement happened. The DELETE statement successfully completed. That it was rolled back is great, but the DELETE statement still successfully completed.
If you don't like that ROLLBACK and COMMIT are not captured by PgAudit, open a Request For Feature issue: https://github.com/pgaudit/pgaudit/issues. Or write a patch then submit a pull request.