The simple thing is: You might want to try to change such things but there will always be bad people everywhere. I can see them making it a topic and it would be great if nothing like that ever happens again but I also would find it quite unrealistic. No matter how great most people are and how much Hien cares there will alway be those that will hurt others. They should try to talk to the people and that those wont turn away if they see something like that but more than that would go into the realm of fairy tales imo. Even in our modern world we have problems like that.

A grave for her would imo be too much. No matter the past she still committed horrible crimes. Its really bad that there were people mistreading her but that gives her no right at all to kill and torture any other person in this land. Her getting a chance as Tsuyu was probably more than enough for what she had done.