Acoustic Panel Help

Adding room treatments without measuring the room performance is not a great idea.

You have a very reflective (bright) room as it is. Are you sure you want more diffusion? If you haven’t already done so, try covering the cabling behind the speakers with blankets and then noting the results of the sound absorption. I'd even cover the screen when not in use. If this is not to your liking, then try diffusion. Best of luck.

You might consider putting a blanket or quilt over your flat screen when you’re listening as well as some diffusion. Book shelves & CD racks can work in a pinch as diffusers.

All the best.

I would first put some sort of absorbent material back there, like the aforementioned blankets or even towels (temporarily) to see if lessening the reflective sound might be an actual improvement.  It sounds like your Maggies are pretty close to the wall if your TV is right there with them.  Planars or stats are usually happier farther out in the room.  Figuring that out could tell you what you put on the frames you're talking about building, hard, soft, or diffusing like Vicoustic. Putting some kind of tapestry up, you could just lift them to get to your cables.  Sounds like your electronics are below the screen.  

With the amount of toe in you have are the speakers even firing directly to each side of the tv to make any treatment effective? I also agree with the above posts that some absorption would be in order. Good luck!