What are they going to charge her for? There aren’t any victims of her murders in this world.
That's why the little judge couldn't declare her guilty -even if it could see all the people she did kill, the laws of the world they're in now don't apply to her actions in our world. Made the poor thing BSOD.
That said, she's still got blood on her hands and is experienced in fighting people, so by their standards, they can't just let her walk freely and risk the chance that she turns her blade on another person, especially since she's proven capable of going toe to toe with a high-ranking hero. They've got to come to a legal decision that'll set precedence for how to deal with otherworlders like her, and ensure that whatever nations are in that world recognize said decision (especially since some of the races can clearly tell she's killed people just by observing her).