So that's essentially a declaration of "Fuck you, I'm evil." So... If it's in somewhere like Beacon she would call for help and make sure someone else takes care of Carmine while Malina goes to try and off Leo and most likely die in the process.
If it's the City, she knows Leo is a Beacon student. She knows that tomorrow, he'll be in the building. She knows that she can find his team room. It doesn't matter if she has to force her way through Ayla, Umbra, Soljia, or Gaia. She's getting to Leo and she's going to die. Before that, though, she'd make sure Carmine gets proper medical attention.
Titania immediately gets Carmine to medical, no matter the location. After that, she's not Malina. She won't charge blindly in to fight Leo. She's a professor, she's the assistant headmistress of the school. From that point on, she does everything in her power to get Leo permanently sent back to Pilum. No physical presence, not calls, no video monitoring, nothing.
Titania, knowing what Rose has done in the past, would take that very seriously and question why the hell they tolerate him being here.
Titania is still a teacher, she can still administer punishment to her students.
Same as above.