A false confession manhwa novel is interesting because it plays with your expectations. You think you know what's going on based on the confession, but then things start to unravel and reveal a much more complex story. The element of surprise and the exploration of truth make it compelling.
The big distinction is that a false confession manga can show actions and expressions directly through illustrations. A novel has to paint those pictures in the reader's mind with words. And sometimes, the complexity of the plot and character development can differ based on the author's style and the limitations of each form.
Well, a 'a false confession light novel' could potentially be centered around a complex web of relationships. Maybe the false confession is made to protect someone the protagonist loves. It could also explore themes of justice and how a false confession can disrupt the legal system within the fictional world of the novel. It might also deal with the psychological state of the character who makes the false confession, like their motives and the internal struggle they face.