This is very interesting and enlightening!
Just a casual observation - I've noticed that word choice seems to be important to both of the people in this conversation. Specifically, it's something I've noticed in Auburn for quite some time. Could this be a Ti effect? It seems the priority lies in conveying an idea with extreme accuracy, even if the words used are somewhat obscure or difficult to understand. Perfection of information transmission over universality of information transmission.
I almost wrote ease instead of universality, but then I realized that, to the Ti user, processing words with highly specific and accurate meanings may be seen as easier than a clumsily put together phrase that anyone could understand. Could this be Ti priority over Fe? Or is this more of a Ji effect? I personally agonize over if my ideas are comprehensible or not, but that's because I am highly disorganized and am not good at conveying ideas.

I like the gem of a quote you chose to open this with @auburn. I have a need to improve my social skills, and I always appreciate chances to hear perspectives of people who are different from me in ways that help me see my blind spots. With this comment in particular, it's rare to hear the other side (a non-Fi user on expressing difficult emotions and the meanness or niceness of it) explained objectively and rationally, instead of while in a state of anger or disgust. For a long time, I had just assumed that everyone thought that expressing emotions was just a part of human life. And that sometimes the truth (factual or emotional) makes you uncomfortable, but it is important nonetheless, if you want to gain clarity and get to the bottom of a situation. That hiding one's true feelings is a red flag, and can often be sensed. Since to me, the potential reasons to *not* express the depth and breadth of my emotions include the following: I am trying to pull one over on you, I am trying to manipulate you emotionally, I do not trust you enough to open up, I perceive you as unstable and needing to be walked around on eggshells, I don't like you and am mocking your inability to see through my fake happy-happiness, or I do not believe you are worth the trouble (or are capable) of coming to an understanding with, so I decided to give up on our relationship and just be placid and allow us to continue never seeing eye-to-eye. And since none of those is good, I did expect everyone to be ok with expressing emotions, even when it's temporarily uncomfortable, as a necessary condition of being honest and aboveboard. Quite the opposite of having bad intentions or being mean. Only when I started learning about typology, I learned that emotional expression means something very different to very many people, something which I am still working on understanding better, in order to coexist better with more people and be on each other's good side.
Funnily enough, the observation you first mentioned @Alice, while it could potentially be its own thread, I also see as related in a way.
It has been observed before that high Ti users are very particular about word choice, and that every detail of what is said is factually accurate. In another group there was a debate between Ti and Fi users on this, and I noted one of the reasons give by Ti users for doing this, even if it is annoying to some (such as when they are interrupted with technical corrections), is because they care about the other person, and therefore do not want to let them keep going with incorrect information, because it could potentially lead them down a wrong path and cause problems for them. It's really kind of analogous to the Fi scenario above. In both cases, people, when they care about someone, want them to have as much access to the truth as they are able to help them get. They do it in different ways though, relating to where/how they believe the most important truths to be arrived at: by way of rational thinking, or in more emotional ways. With the head or with the heart.
As for the rest of this thread, tbh I didn't even get through all of it! But I am looking forward to "Discussions with Jelle on P axes" 🙂