Seeking a novel where the female lead of an anime and manga exchanged worlds with another male character in a parallel world due to the dissatisfaction of the audience.

I'm not sure what the novel and anime you're describing are. However, according to some novels and anime that I know of, there might be a plot similar to what you described. One of the possible novels was The Attacking Giant. In the novel, the female protagonist Alan's mother was eaten by a giant, causing Alan to have a strong hatred for the giant. Alan had tried to kill the giant through close contact with the giant but failed. Later, Alan met another heroine, Rainer, and decided to escape the attack of the giants with them. They achieved this by exchanging worlds, but in the end, they found themselves trapped in different worlds. Another possible novel is Your Name. It was a story about a young man and woman who swapped bodies. In the other world, the male protagonist Long Hong was a high school student and his twin sister Long Bai was a middle school student. Long Hong tried to find a way to return to her own body while Long Bai tried to understand his experience in the other world by interacting with Long Hong. I hope these answers will help you find the novel and anime you want.