As an update to my own question, I spoke with an attorney at the FDIC, who stated that no, a Formal Trust does not have to bear a "real" name. To qualify as insurable, however, it must be a "testimentary trust"; the intent of the grantor to pay funds to a named and qualified beneficiary must be clear. Because we only had the Certificate of Trust Existence, she suggested contacting the customer and asking who will receive the funds in the accounts titled in the Trust when he passes away. His response will give us more information to be able to determine whether or not the funds are covered in the Revocable Trust category.
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Opinions are mine and never to be taken as legal advice!