The Trader Princes developed out of a caravan route between Safelster and Esrolia that was established around 1200 ST. Caravanserai needed to be established and fortified, alliances needed to be made with local tribes, mercenaries hired, etc. Eventually these caravanserai became the nuclei of small cities, and the centers of tribal confederations led by a Trader Prince.
The Trader Princes also claim the Malkioni status of talars. They claim descent from Issaries himself, and from Froalar son of Talar, son of Malkion, on the distaff side. The Trader Princes maintain caste taboos, including Malkioni zzaburi advisor/wizards (usually recruited from Safelster or Seshnela), and offer worship to the Invisible God. This aids them in dealing with talars in Safelster and Seshnela. That being said, they largely subscribe to a Lightbringer mythology. The Trader Princes, unlike most Manirians but like most Malkioni, trace patrilineal descent.
All of the Trader Prince dynasties are centuries old, and are married into the local population and/or have Esrolian (or more rarely Safelstran) spouses. Their actual connection to the ancient founder of Seshnela is fantastically thin, but they still claim it (and among Malkioni, they play it up).
We can imagine that after four centuries, these Trader Prince dynasts form a small group of interrelated noble families. Perhaps it is normal for a young Trader Prince to spend a few years in Nochet or Safelster, to build up connections, learn from the locals, and so on.
I don’t view the New Hrestolism of Loskalm as particular pragmatic or openminded. In fact, those are two words I’d likely never use to describe them. They are philosophical idealists. I suspect the Rokari are far more pragmatic than the New Hrestoli.
The Trader Princes are Orlanthi with a superficial veneer of being Malkioni talars. They follow their caste requirements around, perform the Invisible God ceremonies, and so keep their status. But Issaries, Orlanth, Lhankor Mhy, etc., are their real language.