I would ghost the center channel completely and use good in-wall left/right mains instead. Talking about putting a center channel in the wrong location when you KNOW it is the wrong location is not the way to dot things.
You had an interior decorator put a fireplace in a room that makes the women swoon, then you sit around all Spring, Summer, and Fall with the fireplace off and a crick in your neck from staring at a TV that is located WAY WAY WAY too high.
Someday...
Someday they will figure out that the family room is a primary TV location. If the TV goes above a fireplace, the fireplace will be designed as a wide, low height model, far closer to the ground so that the TV can be placed lower, and there will be plenty of room to get the speakers in place where they belong.
I mean, the mantel is like 20 feet off the ground in this room. Why would they even do that except to ensure that a TV can't go in the place where it was designed to go?
I HATE home builders and their decorators. Go into a model home and see where they put the TVs and see if that's acceptable to you.