re: Is some sort of mold inspection required

The whole certificate thing is made up, it really has no value. You can get a test from an industrial hygienist, I think all good mold remediation companies use a third party. They will tell you if you have more mold spores inside than outside. If you do, it can be treated. if it passes, it's just for that moment, who knows what would happen 5yrs down the road when a faucet starts leaking and gets at material that wasn't treated properly. Probably the same that would happen if it never flooded. It would grow mold, mold spores are everywhere. The flood didn't bring in crazy mold, it was always there.

Like a previous poster said it might be a good selling point for you to have one because there will be some buyers wanting a sense of security .It's more important that you know that you've done everything possible to remediate any possible future situations, like pull out cabinets. no shortcuts.