Flamestrike
Legend
Yoda has no connection to the knowledge and training that leads to Sith Lord.
And Ashoka has no connection to the knowledge of a Jedi Master. She is not a member of the Jedi tradition and does not adhere to the Jedi Code, so she cant take levels in Jedi Master!
From the rules:
Jedi Masters represent the pinnacle of the Jedi order. They are Jedi who are both strong enough in The Force, and patient enough in life to pass on their skills by teaching a new generation of Jedi. The journey from Padawan Learner to Jedi Master usually takes decades, and many who start upon the path never reach its final destination.
She is not a member of the Jedi Order. Her journey in the Jedi tradition from Padawan Learner ended when she left the order after being offered the rank of Knight. She never reached the 'final destination' of Jedi Master.
Further, a Jedi Knight usually doesn't become a Jedi Master until they train a student to completion.
She hasnt done this either; either be a Knight or train a Padawan to Knighthood.
And most importantly:
During the Rise of the Empire era, the Jedi Council would confer the title of Jedi Master upon those deemed qualified to teach others in the ways of The Force. During the Rebellion era and the New Jedi Order era, Jedi require no such approval; however, they must adhere to the tenets of the Jedi Code to become Jedi Masters.
Ashoka Tano does not adhere to the Jedi Code. She is no longer a member of the Jedi force tradition, and as such she cannot become a Jedi Master, any more than she could become a Sith Lord.