For now, this is personal opinion, not fact: I'm in the camp that disagrees about the Vex being created by the Traveler. You have some strong points about why the Traveler could have made the Vex. However, in the span of the Destiny canon, it simply doesn't make sense that the Traveler created the Vex. Assuming that you're right about the Traveler creating the Vex, this timeline is pretty much on point. Good job!