I've generally found clearing passport control and customs at CDG to be extremely fast and easy. On my last trip it was less than 10 minutes from the time I walked through the door of the terminal to waiting at baggage claim, and my bags were out in another 5 minutes. The one potential delay I could see is if the inbound flight to CDG arrives at one of the hardstands. Waiting for the buses, then making the trip over to the terminal, could take longer than clearing passport control, claiming bags, and walking to the other terminal.

But if the flight arrives on time, she moves quickly, and tries to get a seat near the front of the plane so she can be one of the first ones off, and toward the front of the passport control line, and follows the suggestions here about changing terminals, it's doable.