So, I wouldn't mind her exposing the "existence" of her ability, as in, the possibility of connecting Lua's disappearance to "teleportation", as unintentional, if we didn't get the first half of the first chapter, and we didn't get her subconsciously reveling in the murder of a bad person.
1. The MC was introduced as having already experimented with her power. It is not known for how long she has had it, but assuming she is still testing it at this point and how she performed in a real situation, I can reasonably assume it is recent.
- Trauma-related? It'd be interesting if it manifested as a response to an unfulfilled desire to save her father in time, perhaps.
2. She is able to calmly judge and assess a situation under stress, but for some reason, the author thought it was a good idea to have her teleport in an area with concentrated attention. I get she wanted to save the dude, but none of this should've happened because WHY DID SHE INVITE HIM TO A LOCATION SHE'S UNFAMILIAR WITH!?
She already suspected him of seeing her teleporting with Lua, which is reasonable because it'd be an insult to the audience if he didn't, so why didn't she take him somewhere familiar?
Assuming this event was going to happen near her anyway for plot reasons, If she was somewhere she was familiar at, she could've had more options to deal with the situation.
All of that said, I can't think of any way this situation could've turned out differently unless the knife guy event got deleted and her classmate confront her the next day when Lua's death is announced and he asks her the "how" question then.