I see a minor issue with this: The Herald that dies, dies most likely at night. Since that's when Szeth does his assassination. Shallan says in reference to her mother in WoR, "Our mother was murdered, that night Jushu held me." (WoR 563) Which I would say, seems to imply the mother was not killed at night . of course it isn't certain the mother didn't die at night, and that is why I think it is only a minor problem.