Her accent was nearly flawless. I haven't heard that accent on anyone under seventy in years.
Some of your complaint may be with the director. I happen to like the guy, but he is eccentric. A protege of Robert Altman.
And since my family has lived in Manhattan for MANY generations, I have heard, since birth, many different New York accents, most of which no longer exist. I'm still pretty good at telling, just by hearing someone speak, where in Manhattan they grew up and when.
Oh, the director was an Altman protege? I didn't know that, but it dies explain quite a lot about that movie.