Nice system. I notice you have a subwoofer tucked into a corner. I do think diffusors would be good, if 3D, consider ceiling diffusion and absorption as well as combinations at the sides as well.
Keep in mind that you might want to use those corner spaces for bass traps. Measure and consider your bass response and room modes first, and then decide on corner bass traps and then decide on the rest with the remaining space.
Consider movable curtains in front of the TV. Experiment with a blanket over the TV to see if you hear meaningful impact or not.