If you don't mind me asking. You wrote that Grand Moff is number 3. Was that described by some canon Star Wars source or did you just make the logical assumption?
I was merely basing my opinion on what other governmental structures we can identify in the game.
Darth Jadus is a member of the Dark Council and the head of the Sphere of Imperial Intelligence. The head of Imperial Intelligence is the Minister of Intelligence, who has to answer directly to Darth Jadus.
Then, during the Black Talon flashpoint, Kilran introduces himself like this: "My name is Rycus Kilran. I'm commander of the Fifth Fleet, second to the Minister of War
, and—my personal favorite—the so-called "Butcher of Coruscant.""
Based on these information, I came to the conclusion that he could technically be the number 3 in terms of military command. Likewise, he is the only Grand Moff we see in the game, unless you count