But that's not it?
She tries to find excuses about how she found out about goblins, but why would she do that in the first place, if those children are supposed to prove themselves?
She could've just show that she's strong, but still let them do all the work, it's just an excuse for the "I will not tell anyone how strong I am until something bad happens" trope
Err no that’s exactly why it’s this way. She is supposed to let them do the fighting but she, because she’s wasn’t given much guidance, isn’t sure how much help she is allowed to give. Is telling them about the enemies allowed or is she supposed to let them figure out everything and see how resourceful they are.
Also if she had told them that she was the one who sensed it then they wouldn’t believe her as they think she bought her rank and that she’s a spoiled rich girl. It’s better for them to think the bears are the ones who sensed them as they’d buy that than a weak rich girl being the one to have found them. As someone else stated, would you suddenly believe the words of a child if they told you they were one of the riches people in the world? Or would you instead think she’s lying about her status and wants attention.
Also they were told how strong she is they just don’t believe her and think protecting her is part of the test. Her strength isn’t really hidden from them as they’re told from the onset how strong she is. Afterall it’s not like she can fight monsters in front of them as that’d be her failing her job as a tester.