But truths proposed for definitive belief by the Church can also be proposed by the canonical power, in which case they are believed with ecclesiastical faith and not divine faith. In the case of some such truths, they are not contained in the deposit of faith even implicitly, but they are necessary for guarding and expounding the deposit of faith. Such truths include the solemn canonizations of saints and the condemnations of Quanta Cura - and those who deny them separate themselves from the Church.
"My point was merely that the act of imposing the doctrine would prove it wasn't a 'novelty'."
If it never was taught before, nor even disputed, then it would be a novelty.
"Such truths include the solemn canonizations of saints and the condemnations of Quanta Cura - and those who deny them separate themselves from the Church."
Not true. Denying that solemn canonizations are infallible would not be heretical.