To be fair, making Darth Vader a woman rips the entirety of Star Wars Saga to shreds, it would change absolutely everything. you could make Luke a female or The Emperor or Yoda or even Han Solo, but, with making Darth Vader a woman it wouldn't really be possible to tell the same story
"No, Luke: *I* am your mother!"
There's nothing fundamental about Vader / Anakin Skywalker being male that's paramount to the story. The important part was he/she gave birth to Luke and Leia, and passed on the Jedi powers (and savior stuff).
He was basically androgynous in eps IV-VI. And the fact that he was male in the first three? Ehn. Starbuck and Boomer were recast as women. It was just a reboot.