I typed that right after I got home from a long hike, and i fell and hit my knee on the way back, so I was rather tired when I last replied to you.
The point being is that since some trust in a central authority is required, the central authority can handle verification. And because of the cryptographic signatures, the only way they could cheat would by ommitting transactions. Invalid transactions, either because its unsigned or because the numbers don't add up, can be detected trivially. So if we just give all stakeholders a copy of the transaction, they'd be able to prove that the transaction has been ommitted.