The Immortal Cultivation World is full of mysteries, and one cannot rely solely on what they see with their eyes. Sometimes, intuition is important.
This time, Yang Dan's primary aim is to have her little brother apologize to Chen Yi in an attempt to alleviate any enmity they might have accrued over the years. Even if there is a slight chance that Chen Yi might be responsible for those incidents, these apologies serve as an assurance for her future.
Secondly, she wants to personally assess Chen Yi, to probe his cultivation level, martial methods, and use secret skills to sense her talisman treasures, puppets, and Aunt Qin's quasi-magic weapon.
So far, Chen Yi had seemed impeccably normal, indistinguishable from any other cultivator at the Foundation Establishment stage.
While attempting to subtly sense these treasures, Yang Dan didn't find any evidence of previous ownership.
Seems like it was a mere coincidence, all those incidents probably had nothing to do with Chen Yi.