Sure, it's uncouth. It's not quite obscene, but it is definitely declasse.
You might want to point out to her that excess use of such mild expletives can result in their habitual use, so that she wouldn't even notice that she is using them until they fly out of her mouth in totally inappropriate situations. Like a job interview. That would go over like the proverbial lead balloon!
You might want to tell her that continuing to use language like this reveals a poor command of the English language. She ought to be able, as a high school graduate, to express verbally and in the written word degrees of emotional intensity without resorting to "freaking," or worse.
Should she meet such an admonition with a blank stare on her face, and especially if she persists in using such expletives, might I suggest that you buy her a couple of books for her next birthday, or for Christmas? An etiquette book and a dictionary come immediately to mind.
That ought to get the point across without resorting to "preaching"!