I'm going to disagree. I think in this situation is was a failure. Sure you can tell yourself that it should be caught now (and it should) but don't consider a rollback successful after you had reviews and meetings and still missed something. That is a failure. Of course, you won't do the same thing again and you'll learn but a 'good' team will feel bad that they missed something. You (the team leader) can celebrate that the team cared enough to feel bad and cares about the work but don't make an excuse for the failure.