In regards to the traitor; Rudolph was contemplating the suspicious falling out between Oscar and Wilhelm right before he mentioned the traitor. This was something that supposedly happened about three days ago and this only reached Rudolph's ears now. And it came from Sheila of all people.
The reason why this might be weird, is because he had a spy mark Wilhelm for suspicious activity:
See chapter 13.2
Yet, no information leading up to this supposed falling out (or maybe the plan to make it sound there was a falling out), nor information about the falling out itself was reported back to Rudolph. So if we assume that people aren't incompetent, it stands to reason that this information was deliberately suppressed by someone. If not Anne who was supposed to mark Wilhelm, then someone who was supposed to report this information on Anne's behalf. Which might be Maya, given that she's shown there in the end.
While that would be a crazy twist, I think that would be too crazy of a twist to make Maya a traitor. Anne on the other hand hasn't had enough screentime, so she could possibly be a traitor.