You are correct, the number miscount on the travelers is due to the many buy phases you had.
For the choice of what picture to use to represent the exchange, I agree that it was something to get used to at first. The ideal solution might be showing clearly what you potentially give up and what you would get. If that can be done in one picture I don't know.
Mostly I think showing you what you potentially get makes more sense, because if you click on that button, that is what you are getting, and that is what you should be the most important part of the decision. But I see the counter argument that you want to keep you Warriors and Disciples and focus on that, instead of "not wanting" Hero or Teacher.