Mindy is perfectly welcome to run into Penny or Justin! Justin was trolled by a previous Mindy; if you need someone to be Thoroughly Unamused by her all the time, he'd be good for it. I don't think Penny would be all that great at telling her to keep the swearing down. Too much of a pushover.

And Chekov thinks that Mindy's hilarious. He won't be a bad influence, but he'd be happy to teach her to swear in a few other languages.