Watching again, Wen Ning thinks he might understand it a bit better the second time around. He can contact different rooms on the train to talk to people if he knows someone is in one. The problem would then be knowing where anyone was at any given point. Or he could contact the whole train and ask, but he thinks he'd be a bit too shy to do that.

"Is there... any way it can tell you where someone is?" That sounds like complicated magic, but the train can do so much already that he doesn't think that much would be beyond it. If it doesn't, he'll just have to keep better track of his friends.