Spoilers for the second Hathaway film.
Gigi never casts a spell. She has no wand. Yet people keep changing course around her. So when the film calls itself The Sorcery of Nymph Circe, is it naming Gigi as the witch? Yes, in a sense—but the title is doing two jobs at once.
First, Circe is a military name
Kenneth leads the Federation force hunting Mafty. That force is called the Circe Unit, a name adopted after Kenneth took over from the previous command. Circe herself comes from Greek myth.
It is a wonderfully Gundam sort of trick: you arrive expecting a mysterious woman and discover that the military has already put the witch on its letterhead.
Then there’s Gigi
The official description of Gigi draws an explicit parallel between her influence on Hathaway and Kenneth and the magic of Circe, who enchants men. Her actions bring their paths together.
That doesn't mean Gigi is secretly mind-controlling anyone. She follows her own impulses. Kenneth pays attention to her uncanny instincts; Hathaway is shaken by her presence. Decisions ripple outward, even when she doesn't set out to change a military operation.
No spells on screen. Potential consequences for an entire operation. That's why the witch comparison lands.
The two meanings reinforce each other
The Circe Unit is an actual organization in the story. Gigi is associated with Circe through the way she affects people. Neither cancels the other. What we shouldn't claim is that Kenneth named his unit after Gigi—the evidence does not establish that.
The title links a military hunt to the woman caught between its commander and its target. Gigi may not own a broom, but she hardly needs one when two men and a war are already flying around her.
