This is exactly what I tried to do! But I am just a mere Scooby Doo-level amateur butt detective, compared to your Sherlock Holmes of assness, good sir. But here's my unschooled take, FWIW. Nothing at all obvious like Ivy, as brother Night reports. More plausible than P31 Love's wonderful buns, that had me completely fooled, because as you later correctly pointed out -- and in retrospect I should have realized -- that Love had just a bit of softness in the belly (which I found endearing in a way) that didn't really make sense with her firm meaty tushy. Chanel here has the overall fitness physique that blends in perfectly with this queen of all bums. I tried my darnedest to find evidence of unnatural bumps or ridges, but I couldn't find anything. Then again, I don't have your expert knowledge of rear physiology - I don't even know how many different muscles I'm supposed to feel, much less their names, other than the gluteus maximus. (Is there a gluteus minimus?) At a certain point, I had to stop playing detective and just enjoy the ride.
In my heart of hearts though, I think she's had something done. Her older Sally's pictures, while nice are clearly not as good, and I'm sure you would have remembered THIS ass more clearly if it had been that outstanding. It could have been honed through an intense exercise regime - but I don't think exercise alone can increase the mass at the 2:00-3:00 and 9:00-10:00 regions, can it? That's the area, in contrast to her waist, that takes it from a great ass to a whole other stratosphere of bonkers insane ass. Basically, it's just too good to be true. For any ethnicity, much less for a Korean. But if it's enhanced, man, what a Michelangelo of surgeons. And obviously Dr. dude did a bang up job upstairs as well. I bet she's had stuff done on her face too (lips in particular), but it's subtle and totally natural looking. (Given the fine work on display here, maybe it was full team of specialists involved).
I think we're at the point that you, and only you, can go in and fully certify and authenticate. I don't care how many times you have to bang the MMS to get past that door and into the room with Chanel. Just do it.