> That said, the consensus I've heard from my audit colleagues (I work in public accounting) is that no one has the slightest freaking clue how to audit crypto.

Shouldn't the crypto part be trivial for Tether? You'd just need to check how many Tethers were issued on the blockchain. The hard part ensuring that those Tethers are backed by real Dollars - and that should be a regular accounting task that doesn't have anything to do with crypto.