Of the 8 screenplays about women writers that you cite, only 2 were written entirely by women.

Also: Agatha (male and female writers); Romancing the Stone (female), Jewel of the Nile (male); Atonement (male).

Not only are women underrepresented as writers in movies, but the experience of women writers is filtered through the experience of men writers.

And how many movies are there (by writers of any gender) with women screenwriters as characters?