Looks like Joss Whedon was punished for not writing Black Widow in the way that feminists would approve of.
When it comes to writing female characters, the same rules apply as when writing male characters. It’s not extra hard. A female character can be good or bad, strong or weak. Just don’t make her boring or wooden.
It only seems extra hard, because writers allow themselves to worry about what the PC police will say. When you start worrying about that, you invite extra writers into your head, leading to the “too many cooks in the kitchen” effect. As a result, you will have a political tool, not a living, breathing character. And then it’s no wonder it’s not good.
And therefore, I think the key to pleasing feminists is to ignore them, forget them, and let your creativity flow.