It has historical precedent. In a situation like Warhammer Fantasy, where you both have restrictive travel and communication times, as well as brewing international crises that require an immediate response on the scale of Chaos, Orcs, Necromancy, etc, it seems very reasonable for Lord Magisters (as well as other high noblity, high priests, etc) to be effectively given
plenipotentiary powers when it comes to decisions that are within their area of expertise, rather than those powers being restricted only to distant governors and diplomats.
It's not just that, it's also that telling anyone at all would go completely against operational security. The less people know about something sensitive, the less chance of someone leaking it, or abusing it. This is how the Grey Order operates, which Boney has been consistent on for a long time.
Consider the Liber Mortis: The more people know about it, the more people might be tempted to find copies of it and abuse its knowledge. If you possess a copy of it (and you won't destroy it because you want a contingency plan in case another vampire tries to become a Von Carstein Emperor), then it doesn't really benefit you to share that you have it, even with another person you trust, because then you have
two people who could spill the beans on it or go mad with its power. This way, it's a single potential point of failure rather than multiple.
Similarly, if we go to Algard or Dragomas or Luitpold about this,
even if they were to say 'yes go do that', they would lose the capacity to truthfully say, even under magical interrogation, "I swear I didn't know this Lady Magister killed/attempted to kill a foreign head of state."
Hence, the decision is up to us. We have the capacity to do this solo, and it is our Order's job to do things others would never consider if it is necessary and to be taken to the grave.
I'm imagining Eike rolling a natural one on her study action, and somehow catch Mathilde red-handed after killing the king. Do you think she would ever tell anyone? Like, divided loyalties jr. edition.
Eike, thinking to herself:
I heard the previous Tzar died, which allowed Master to start spreading tributaries across Kislev more easily alongside the new Tzar, Boris Bohka. And now that I think of it, Master came back that month in a morose and withdrawn state, I could feel it through my Magesight. Why would she be in that emotional state despite such a great success? And why were her robes be somewhat out of place the day after she came back? There's only one logical answer...
Eike, out loud: "Master, are you having an affair with the Tzar?"
---
...Actually,
does Eike know about the Waystone Project proper? Cause I went back through the first turn we had with her and it sounds like she might have the impression we're only here to build bridges via trade and diplomacy. We haven't included her in any Waystone actions yet, either. It'd be really funny if she only found out when she set out to become a Journeywoman, or when Teclis came back.