I like it :P It makes me think 'old', because in my mind
Cornelius is irremediably an old Merlin-type scholar/alchemist with a gray beard :P But that is more easily overcome with
Cornelia. I'd go with
Cora as a nn.
I like
Cornelia Marian,
Cornelia Bridget,
Cornelia Amaranth,
Cornelia Briony,
Cornelia Harriet,
Cornelia Nimue, and
Cornelia Elspeth. Also
Cornelia Sage,
Cornelia Briar,
Cornelia Rose,
Cornelia Igraine,
Cornelia Pollyanna,
Cornelia Polyhymnia,
Cornelia Undine,
Cornelia Ursa,
Cornelia Saskia,
Cornelia Senka,
Cornelia Artemis,
Cornelia Athenais, and
Cornelia Pelagia.