Hi and welcome on-board this HT system config. thread.
First off, here's a big congrats to you for your fantastic setup. Especially for the DIY jumbo screen which already make me jealous!
As regards the audio setup part, I may have a few comments to you if you don't mind that may improve the SQ (Sound Quality) a bit.
1. Center speaker: if you pull it closer to the front edge of the cabinet and find a creative way to tilt it upward (you're good at such sports as I can figure) LOL, to make it face seated ear height at the MLP (Main Listening Position), i.e. practically the middle seat on the couch it will result in improved dialog intelligibility. Speakers not only deliver their widest frequency range when on-axis to our ears, but also deliver their highest SPL (Sound Pressure Level) as well. Worth to try, costs nothing!
On a second note a carpet or rug between "coffee table" (or that standard pallet) will tame so-called reflections in the mid to high frequency range, again improving intelligibility of dialogs by lessening so-called "smearing" of sounds. Costs some amount, nothing dangerously expensive should be considered.
2. Front Left & Right speaker positioning. Best results can be achived for sound stage imaging when toed-in (angled) toward the MLP. See explanation of speaker behaviour as above.
3. Surround speakers: can't comment coz I don't see them on your pictures.
4. Subwoofer: can't comment again coz I think you haven't purchased one yet (at least it's not in your equipment list). A subwoofer is usually regarded as an integral part of a modern Home Theater system. A sub with a driver of 12 " or higher is considered a sub!
5. Reflective glass surfaces: any female member in the family I'm sure would be glad to assist you by putting up some kinda light curtains that would help again to tame the room's smearing and greatly improve pin-pointing different sound sources in your room.
Seemingly these are small issues but in the end they all can add up to a substantial overall improvement of the SQ in your HT system.