Helping the disciples as Charlotte is against the point of starting over! The Emperor was an exception, and she didn’t need gloomy boy to think she was Charlotte for long, so she better clear things up once the brainwashing is broken!
We don't know if she has communication with her mother's side, so I'm guessing her powers are subconsciously manifesting.
Side Note: An Admiral is equivalent to a General, which is two ranks above Major General.