What’s to “audit” regarding monetary policy? Those decisions are open records. Every decision is the subject of Godknows how much public dissection and discussion. People may disagree about monetary policy “a” or “b”, but there’s nothing secret about any of it and there’s nothing really auditable about such decision-making processes.
Auditing is about verifying transactions and backing up financial statements with trustworthy documentation and testing. Auditing is not about disagreements with various executive decisions.
We should be able to know why they do what they do so we can understand whether or not they are playing favorites. They have to have reasons for what they do and they should have good reasons.