There are no federal legal requirements that you obtain board minutes or documentation in support of changes in signatories. It's purely a matter of due diligence as implemented by bank policy. Accordingly, the only source of "exemption" is your bank.
Giving the Treasurer the benefit of the doubt, it's possible that other banks have told her the municipality is not subject to CIP. That's true, but irrelevant to documents demonstrating who has authority over the account.
This is an odd source of resistance; such meetings would generally be "public," and most states have "open record" laws. Generally, anybody could see those minutes and obtain copies.
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In this world you must be oh so smart or oh so pleasant. Well, for years I was smart. I recommend pleasant.