While the Magic: The Gathering Companion app does allow players to input their own match results and verify their accuracy, mistakes may happen. With round rollback, you can fix an error in a match result up to one round after it occurs.
Once you roll back a round, you cannot undo it. Additionally, you can only go back one single round. This ensures data will stay accurate in your event. Be sure to carefully consider the impact on your players before deleting round data.