Lerasium wouldn't be of much help to Hoid. From what I understand, you only have access to the magic from whatever world you come from. For example, if someone from Scadrial were to find themselves on Sel, they wouldn't be able to become an Elantrian or use the Aons in any magical capacity. So, unless Hoid is originally from Scadrial (which is unlikely), lerasium is useless to him.