I'm sorry to repeat, but I believe IMDB is correct in claiming Gemma Chan is Quintessa. Check out this interview with Gemma Chan. She says "world" around the 1:43 mark and if you compare it to the trailer, the voices are almost identical - in my humble opinion. Apologies if this repeats the previous post titled "QUINTESSA IS IN THE FILM!!!" lol. Just wanted to provide some evidence here.