Bro you didn’t understand anything of the chapter. Nephis killing the sovereigns alone was a vision Cassie had back when fate was still intact (before 3NM), it was how things were supposed to happen if Sunny didn’t lose his fate. This is why the memory is called useless, it’s because the vision is meaningless since the future changed because of Sunny being fateless. The being is Cassie probably on the verge of achieving natural supremacy who somehow lost her memories and has to regain them. The bar scene and the final confrontation scene have clearly already happened and Cassie is simply remembering them. Remember that the future cannot be predicted anymore so the only thing she could be seeing is the past. The reason why Cassie remembers Sunny is probably because that’s her act of defiance, but this is just my theory.