if you were to 'self-correct', that would mean following the terms of the document, which means moving the $ from Roth to regular deferral, but that involves tax issues so would require VCP
so the other option would be retro amend the plan to permit Roth, but you can't really self- correct something like that without IRS approval, so again going through VCP. I would suspect the IRS would permit that, especially if the deferral election form indicated either deferrals or Roth (as opposed to 'only the owner did this')
at least that is my understanding.