The hardest 'mechanics' in the game right now is TFB Hm Operator IX, and it consist of people remembering what their colour is. It's not rocket science or abstract mathematics, I'm pretty sure everyone can move in and out of colour circles.
Descending the platforms at Soa seems to be surprisingly hard. My last two attempts at it through group finder have failed because half the people died when descending. I'm not quite sure if it was the healers that didn't heal enough, or the other people who didn't stay where the healers could heal them.