No, FAA doesn't deal with configurations. They have regs as to how to balance loads, but that's a hot-to rule, not something you need to get approved or they'd have to approve every single flight. Nothing is stopping Southwest from removign all their seats right now.
The thing is, the FAA and ESA are putting targets for evac times. These have to be adhered to. They are not looking at individual configs, just that evac times are kept and properly tested for.
I'm a commercially-rated airplane pilot. I tolerate the pedantic HN comments, but please realize that I know what I'm talking about, and if you're not a pilot, you don't.
In your mind, if there was only a single rule that seats have to be red, would that count as only allowing "approved configurations"? They have to meet a couple simple measurements, but they can do anything at all inside that constraint, putting seats anywhere they want with nothing stopping them. "approved configurations" just isn't accurate.