I think that the Unmade/Odium Spren are already influencing the world and the people in it. As an example I think Taravangian is actually being manipulated by Moelach. Which is ironic considering Taravangian is how we know about Moelach in the first place.
"There is one you will watch. Though all of them have some relevance to precognition, Moelach is one of the most powerful in this regard. His touch seeps into a soul as it breaks apart from the body, creating manifestations powered by the spark of death itself. But no, this is a distraction. Deviation. Kingship. We must discuss the nature of kingship."
-Epigraph Chapter 82, page 986 hardcover edition Setting up a basement where you drain the blood from people sure reeks of Taravangian's description of Moelach's influence. The Diagram is a misguided (intentionally?) effort at precognition. The diagram even hints that the nature of Taravangian's efforts is a "...distraction. Deviation."