Great analysis. Can you let me know where she goes wrong with the corkscrew? Is this supposed to be like Fedor's casting punch?
So, the corkscrew is basically, twisting your fist in, so your palm is facing the ground as the punch lands, bringing your arm with it, so your wrist, elbow and shoulder joints support your punch, possibly giving it more power and "snap".
The rotation may or may not increase your power, but it definately is makes your punch safer, since you'll not rely on wrist resistance and knuckles only, the whole arm comes into play, the punch is somewhat "harder" and protecting the wrists, also the rotation makes the arm+knuckles a bigger thing and in close distance that works well with punch exchanges, your shoulder, elbow AND knuckle form a good defense to protect you from counters.
Good built in defense is a necessity for good punchers, so corkscrew is common in boxing, not yet in MMA. as you mentioned the casting punch from fedor, which is basically the opposite of the corkscrew.
Now, Edmond and Ronda seem to get the CONCEPT of the corkscrew, but not the execution of it, the way she twists her punch makes it less safe and exposes her more, her shoulder HITS her head from how much torque she puts in it, instead of being one motion only, she breaks it in like 3 motions, in a way her wrist, elbow and shoulder instead of supporting each other, block each other and the power isn't flowing with the punch's rotation, is actually lessened by the motion.
By the time her corkscrew punch lands, she took away all power from wrist and elbow and the punch is almost only supported by her shoulders, carrying 0 power and basically absorbing the pads/mitts impact on her arm. If you do that to someone's head you may get serious joint injuries.