From the link you provided:

"However, GAO auditors are restricted by law from reviewing monetary policy operations and transactions carried out by the Federal Reserve on behalf of foreign central banks."

Also, those audits also do not cover "discount windows" (a financial tactic where banks borrow money from the central bank to deal with liquidity shortages, typically during financial emergencies).

So, unlike the Fed's own audit, this bill would cover much more.

And reread what I had posted.

I haven't jumped onto the concept 100% yet. Even I still have some reservations about it (mainly, what do you use to back the currency and Michigan's record of running things...typically into bedrock) that could make the whole idea moot.