It is pertinent to remember that Matobo, the Ku, and their drowning forgiveness ritual, are all fiction. A scriptwriter liked the narrative and made it up - thinking it sounded like something that would help. In real life? I doubt that anyone willing to drown a criminal would then be emotionally capable of - or honest in - mourning him for a year. Revenge is revenge.
In many cases, survivors can forgive not because the perps deserve forgiveness but rather because the survivor themself deserves to go through the forgiveness process, deserves to feel forgiveness and let go of anger, bitterness, and hate.
I am not one of those survivors. I am an extremely unforgiving person in ANY circumstance. It is a character flaw but it's me. If the man who abused me were to apologize, earnestly, tearfully, publicly, in horror and shame, I would accept his apology and it might even make me feel better. But I would never - WILL NEVER - forgive him while he is alive. Once he is dead I will explore it.
"Don't think it hasn't been a little slice of Heaven just because it hasn't!" --Bugs Bunny