I guess you just can't get good help at Collinwood. Since both Carlotta and Gerard have behaved rather insubordinately towards Tracy, I'm surprised that she never considers firing them. Granted, she may have faced some opposition from Quentin and/or Angelique but Gerard is another situation altogether. Maybe Tracy had this discussion with Quentin or Claire when the camera was not around. Or perhaps Gerard was supposed to keep Tracy distracted so she wouldn't be as able to notice the changes in Quentin until it was too late.
When it comes to Gerard, maybe Tracy felt telling him not to ever touch her again was sufficient enough and unless he crossed that line again the issue had been handled. And as we know, in an upcoming scene Tracy will actually tell Carlotta to mind her own business and Carlotta seems to agree to do so (though she doesn't behind Tracy's back).
But getting back to Gerard, the full script makes Gerard's motivations much clearer with regard to Tracy: he's jealous as hell that Quentin has replaced him in Angelique's "affections" and so he sets his sights on Tracy as revenge. However, that's not made as clear as it should be in the film as it stands because of how the scenes indicating it aren't included - and sadly they're not even in the 129 minute version. But then, so what else was new with DC when it came to including scenes delving into character.