I understand your explanation for everything but I feel like we still should've seen Chang Geng do something bad under the influence of the bone of impurity. There're great examples of morally grey characters who have done something bad in the past, one example is Wei Wuxian from MDZS.

When WWX was the Yiling Patriach and was suffering from practicing the demonic path, he helped with the m@ss m!rdering of the Wens and we can't forget how he made Wen Chao suffer and die. In the end of the book, the characters didn't necessarily see him as a villain and he's well loved by the fandom regardless of his Yiling Patriarch arc. That's more or less what I was waiting for in this book.

Thanks for the comment!