The long post actually helps, in my opinion, because it clarifies both your recent experience and your expectations. I'm going to give you a fairly lengthy reply in return, and I will shoot straight with you
. I hope that's okay.
First, you haven't really been at this very long. You said that you replaced your 20-year old speakers in June, and you just got your new AVR on Friday. The first thing that I think you need is some patience to clarify your own goals a little better, and then some time and patience to execute them properly. This is something you said that may be important: "After the last upgrade to 5.2.4, I starting playing all my UHD and Atmos BD's. I noticed issues hearing dialogue."
Apparently adding more sound sources caused some issues with hearing clear dialogue. If we think about it, that may not be too surprising, if you were already right on the edge with some hearing loss anyway. So, you may need to decide what your real goal is here: clear dialogue, or overhead speakers? You could always try turning off your overhead speakers, in the Speaker Configuration menu, to see if that helps the dialogue.
The second observation I would make is that in your desire to go from zero to sixty in 6 seconds, you have emphasized having a lot of speakers, instead of emphasizing having adequate speakers. Most of us have had to build our HT systems on a budget, and we have built them over time. I think that most experienced HT owners would tell you that it's better, from a sound quality standpoint, to have a good 5.1 system than it is to have a meh 5.1.4 system. (The .1 channel always counts as 1 regardless of the number of subwoofers.)
In fact, I would emphasize the front soundstage even more than the surround speakers, so I would say that a good 3.1 system is the best starting point. The front three speakers is really where the great majority of the important content comes from.
My impression when you posted pictures of your room was that your front three speakers were under-powered for your listening distance. That wouldn't be so obvious with the Left Front and Right Front speakers. But, it could be very noticeable with dialogue for the center channel. Your surround speakers may add to the problem by playing distracting ambient content.
And, your subwoofers could add to the problem because that CC needs a crossover of at least 80Hz or 90Hz, in my opinion. That's to keep the speaker from distorting, which would also interfere with dialogue clarity, even if the distortion were not extremely noticeable by itself. But, as you go up with the crossover, that allows more bass to leak into the sound, making male voices sound chestier and harder to hear clearly. As you noted, accents don't help either.
I don't think that your expectations are unreasonable or unattainable, but you need to take some time to figure things out and to experiment. You need to experiment with the Audyssey target curve and with Audyssey Flat. Which setting improves the quality of the sound for you? No one but you can answer that question. You need to experiment with DEQ on, and DEQ off. Which sounds better to you? You're the only one who counts with that question, too.
You need to experiment with different crossovers for your CC.
And make the changes dramatic, so that you can hear real trends in the sound. Try a 60Hz crossover, and then go straight to a 100Hz crossover
. You can try the in-between increments once you get a general idea of which direction is better--going up, or going down, from the usual recommendation of 80Hz. Take your time, and approach each setting individually so you will understand how it changes things. Otherwise, you won't really learn what you like.
It's your audio system, and your goals and priorities can be whatever you want them to be. If it were my audio system, I would upgrade my center channel first, and my two front speakers second, and I wouldn't care quite as much about the other channels until I got the front soundstage and the dialogue where I wanted them. Along the way, I would take the time to discover for myself what settings work best for my components, in my room, and for my preferences. But, all of that will take a bit of time and patience. I hope this helps!