Kids don't talk like she does. Kobik who's probably about a year older doesn't talk like that. That's how they wrote the olsen twins on Full House. But that was written by 35 year old literature majors who thought they sounded like 3 year olds.
And she's too present and capable of writing to be as illiterate as she's playing.
Romanoff probably could speak to her writing, see what she's turning in.