I don't know. She might be good at it, she might not. But I can understand their not wanting to muddy the waters with a (possibly bad) Russian accent, especially since at leasts much of the time she's pretending to be American.

The "Moose und Squirrel" comment was based on the fact that any sort of strong Russian accent from a female character IS going to draw that sort of joke, no matter how impeccably it's done.

Given that I think they otherwise did an excellent job with Natasha/Black Widow, I'm willing to overlook the lack of accent.