I have a friend who was closely involved in this organization for a few years. What you said sounds exactly right from my understanding. They do not offer many initiations and are not necessarily that "practice" focused. They are mainly focused on the preservation of Nyingma texts and artwork and make huge donations to pretty much any and all monasteries in Asia at the Nyingma Monlam. Tarthang Tulku pretty much lives in isolation on their retreat land and does not receive visitors. he is at least seen once a year by his students at a group initiation/prayer ceremony. This includes many high Tibetan lamas, some of whom my friend witnessed getting embarrassingly turned away at the front gate! He is highly respected amongst Nyingma lamas I have inquired with, but also considered a bit odd for his current disconnect to the current religious/political goings on. Most likely his daughters or older Western students will take over the centers in the future as they are not really a part of the traditional monastic hierarchy. Also the retreat land which is mostly off limits looks amazing, probably one of the nicest in the US.