When using a recessed box like this with HDMI keystones will there be room to plug the cable in, since the box it recessed plus the 1" the keystone will take up, i'm not sure if there will be room to plug the HDMI cable in. The wall cavity is 2x4 construction so only 3.5" of depth.
Assuming this is going behind a TV, you'd be better off using a scoop plate (or nothing) and bringing the HDMI cable directly out of the wall to the TV input. Reduces the number of connections, and also gives you a lot more angle / slack to connect to the TV (which may be parallel to the wall anyway). If the cable in the wall isn't long enough, a coupler would work (same as the keystone).