We worked out a solution. Though as I made my way back to the main peak to carry out the plan, I started second-guessing myself.
Revealing Zhong Yilan's scheme was easy. She didn't go out of her way to cover up the modifications she made—likely because she didn't expect me to suspect the talismans enough to show them to Bai Ye—and any master would be able to discern the differences. But that would likely get her only a scold or an enforced penance, and her master would make sure not to let the news spread.