I don't remember where but i heard a quote from Sandersonw here he said Hoid wouldn't be involved as a major character 'until' Mistborn 7-9. I put 'until' in quotes because hes Supposed to be involved in his origin story: (which actually isn't Dragonsteel) The Liar of Partinel as well as the story about the shattering: Dragonsteel. Although he's been more involved on Roshar than in other worlds thus far, i still feel that he is skittering along the line of non-intervention.
my interpretation of what Sanderson said was that Hoid was likely involved on the events on Yolen in those two series and then theres a long period of non-intervention until Mistborn 7-9 where he is an important character again.