slightly awkward wording here

possibly identify who this woman is - she sort of just appears out of left field.

clarify - is this a column?

possibly rephrase along the lines of "Flanner began what would be her lifelong career as the Paris correspondent for The New Yorker", etc.

"which had just been created"

perhaps include some context as to why the poor reviews of Flanner's book led her to be cold toward Mina Loy. Without any details it leaves the reader sort of confused.

"where they talked [about]"

"and settled in Paris in 1922,"

This wording is very, very awkward; perhaps the two "lived as lesbians together" (were they out in Paris or not? This may be a pertinent detail to include).

"for whom Janet left Rehm" - also, while we're on this annotation, I wanted to point out it may be wise to stick to either "Janet" or "Flanner" when writing the biography, just to be consistent. I would go with "Flanner" but ultimately it's up to you.

I would possibly change this wording to something along the lines of "a decision which introduced"

I don't believe you need a hyphen here.

"in"