Thanks for posting this informative and interesting article here. Hoping to get some more in future.
Incidently I my self witnessed another quality of some of the members of Rongpa Community. In late 80's when my father was posted in Uttarakashi, there were two guys from the community working with him. When they used to talk with my father they used to speak in hamari (Pauri-Srinagar) wali Garhwali but when they used to talk with each other they speak in their own rongpa language. That was really a great surprise for me.
Even now their new generation singers like Kishan Mahipal is singing mainstream Garhwali songs as well as their own rongpa songs with dexterity.