The Unam Sanctam citation would make for a very interesting intra-Catholic discussion. If it was a genuine exercise of infallibility does the degree of submission necessary change with the man holding the office? I mean Benedict seems to have a very relaxed view of what’s required, so too his immediate predecessors.
I am still, however; waiting for an answer concerning it's "infallibility" according to the published formula.
FWIW I have asked the same question many times in the past few years and have yet to receive a reasoned answer.
I do have my own well reasoned logic to explain the absence of a definitive answer:
THERE IS NO CATHOLIC TEACHING WHICH IS SO CLEAR IT CANNOT BE DENIED, MODIFIED, OR RE-INTERPRETED AS REQUIRED!