No, I am not sidestepping at all. I am showing why I think a particular interpretation does not line up. Just because the phrase "that which" is used in both passages doesn't automatically mean they are referring to the same thing. That would be like saying these two passages both use "the" so they must be talking about the same thing. 1 John 1 does not mention anything being "perfect" - and in that passage John was referring to what they already knew and experienced personally about Jesus - so that would be "that which already came," not what is to come.