This was a red light to me: "So, you bring her in, share the feedback you’ve received, and ask if she is aware of the tension. She seems genuinely surprised, because in her view, things have been going smoothly."  Since transparency and honesty are the best ways to get to the root of a problem, Sally first has to acknowledge that she has been abrasive, arrogant, and impatient. If she doesn't see it she will have to have it pointed out to her at the time it's happening. What if the team members, who have been a team and comfortable with their style and habits, feel a little intimidated by a new person who brings new skills and insights to the table?

One option you mentioned is, " If Sally stays and does not adjust her communication style, there’s an easy-to-anticipate set of consequences."  I think if Sally stays she will need to be agreeable to immediate feedback so she can evaluate whether she sees the need to modify her style or not. If not, then HR should provide resources to help in her job search because for whatever reason, her style is not going to blend well and it would be advantageous to the team and to her if Sally found happiness somewhere else.