One thing you really messed up... INFP's have Ne as their auxiliary, Fi is your auxiliary. If Fi were your tertiary, you'd be an IxTJ. If Ne were someone's inferior, they'd be an ISxJ. But your descriptions make sense otherwise.
We couldn't be more different. I don't understand how they think at all, but when I make the effort to communicate with them, they really do seem like nice people who try to do what they think is right first and foremost, even if I don't agree with them about what is right, or even understand how they came to their conclusions about what was right. I'm typically irritated by their tacit confidence that their belief is justified, even though they can't explain it. I want to be nice to them, because I feel and admire their depth (which often seems more than mine), but they have an element I feel repelled by, and they report a similar response to me. So many of the things they say bring out a side of me that reminds me of a disgruntled tech support person who's frustrated with users that can't understand what they're saying until they make it as simple and obvious as possible, and then have to put up that same user complaining that they were condescending, and I don't know why that is. At they same time, they make me feel like no matter what I do, I'm not as good a person as they are, like I'll never be as "real/human" as they are. I don't think it's intentional, but that's the effect.
We can communicate similarly on the surface, at least. They seem to have a lot of energy and zest for life, which enables them to do things I just don't have the energy for but would like to do. It seems like they're more concerned with appearances than I am, and are better at coming across well and responding to sudden, subtle changes in the atmosphere of the situation that I wouldn't even detect. But there's something a little off-putting about them that makes me feel like they want something from me that I don't really want to give, but that they're trying to convince me that I do want it... I constantly feel like I have to be vigilant to avoid being manipulated, because they're just "too perfect." This intensifies when I see them criticizing an INTP's behavior, and it makes me feel like they want to force everyone to live up to their ideal by slow, clever manipulation and distortion of facts in their favor. It usually results me trying to make excuses for the INTP (because INTP's don't seem to defend themselves at all against emotional criticism and let it hit them at full force internally whether it's justified or not, unless someone else defends them convincingly.)
We're similar on the surface, in that we both try to be nice but inconspicuous most of the time, and worry about other's safety and well-being frequently. We both seem to have a good ability to absorb/recall information that interest us. The main difference is that I seem to have a greater need to know why I'm doing something, and seem much spacier, absent-minded, and more impractical than an ISFJ. I don't know many ISFJ's, so I can't elaborate.
They're very blunt, but I can tell that they're doing it out of a desire to help people as a whole in some way, and that they are really passionate about their ideas. They really seem to understand how to make things work effectively in general. They can always introduce a new perspective on things for me, although they can seem oblivious to the exact nature of a system's interconnections and just how/why it works (but somehow seem to make it work). Their passion can help me get motivated to pursue things that are important to me, when they express it. It's almost like they have some of what the INFP's do (that depth), but instead of forcing it on me without understanding where I'm "at," they just reveal it to me in a way I can accept it (and are better at explaining what/why they believe something). It's like the difference between someone trying to force a glass of murky water down your throat, and someone offering you a glass of clean, clear water. I don't know why it feels that way.
That's how I respond to my "off-by-one" types.