What's wrong with the "end system", which is the most authentic terminology directly related to the end to end principle?
i guess there is nothing wrong with it, as long as we define it precisely.
could you provide a definition of what do you mean by end system? would it be similar to JNC's endpoint definiton? or NSRG stack definition?
As I searched reference of the RFC, "end point" seems to be an alternative wording of "end system" that if JNC is saying "endpoint" with the difinition of Saltzer's paper, that is fine.