Well I assume that the translators consciously chose to call Erza a she and her completely ruining the bit where Master asks if it's a woman or a man...you wouldn't ask if someone is a man or a woman after already having chosen to call them she and her...especially when Erza has a clear male physique...so I would guess at first they are using gender neutral pronouns to refer to Erza.
Now I don't throw shade at the okama trope, it's amusing in its own rights.
Just wondering if I am correct in my assumption or mistaken...I would like to see some raws of this.