From what you've said, it appears that your RFO does have the power to determine the format, however, as the purpose of the document is to provide clarity in the management of your finances, it makes no sense to adopt a format that fails to provide you with the information you require. This is one for gentle negotiation and common sense, rather than quoting from the rule books.
I have been working with a council that maintained two sets of accounts, one relatively straightforward and operated by the Clerk/RFO and the other, far more complex and detailed, provided by the Chairman. Unnecessary duplication, but otherwise harmless.