It's not necessarily just “impressions”.
So in both dimensions, they're very inward focused. (Cognitively as well: Si need for familiarity). This, however, is what makes them tend to protect themselves from the outside world with what's known as “concrete structure” or an institution. At least in the conative area (SJ), that is. They don't accept just any “convention”; it must meet a strict criteria of their own. (Like what you said). In a society like this dominated by SJ's, they end up often defining what's “conventional”, but where they're a minority, they would seem more like the descriptions you're using.