Okay, for context, no one knows this person's dead name. They've done a thorough job of making sure it's hidden from anyone, as is their right and I applaud them for that. No one's ever asked because that would be inappropriate, at least to my friend. I don't know if this is the case for all trans folks or not, but my friend seems extremely sensitive about their dead name.
Anyway, so I'm the historian of my class, and all the class officers got a copy of this like 61 page document containing, I kid you not, the name, middle name, last name, student ID number, and birthday of every single junior in our 1700 person school. My friend is listed by their dead name, something I only realized by recognizing their last name and student ID. I put two and two together when the first name listed wasn't my friend's name.
My question is, what should I do from here? About 13 other people who know my friend pretty well can see this document. Should I just leave it alone and assume no one else will notice? Should I tell my friend? I don't want to make the situation worse by drawing attention to it, but I don't want disrespected or put in danger by their dead name being available some place they may or may not be aware of.
EDIT: After reading most of these comments, I have let my friend know. I'll update this periodically as the situation progresses. Thank you all so much for your help and advice, it sucks that as a society we're still dealing with this shit.