Off the top of my head, one way the validation could possibly work is for the tool to auto-respond via email with how it's categorised the data and give the option to confirm or correct it. ("Thanks for responding! Just to confirm, here's what I've recorded:...").

If the user marks it as correct it could have a verified tick or something on the admin side, and then form creators would only have to manually check over the ones without a tick (with the option to see the original text of the user's response and a form to correct the data)

Obviously it would also be useful for the form creator to author the question so that the possible options are given when they're non-obvious, but users don't always read :)