I have full sympathy for your case, but from the airline perspective, I don't know what kind of considerable challenge it's adding to arrive in CDG ay 9 pm instead of 7 pm and connecting to LAX the next day. For sure, no more evening downtown Paris but you can just stay in a hotel in CDG.
And I agree with YVRcockroach, even with an arrival at 7 pm in CDG, your evening downtown Paris will be very short.