Yes in order to trade for more old one tech

I think this time he would do this to protect people from machines (obviously Aloy forced him to do this way).

I think Sylens would be very intrigued by the Quen. Im not sure if he ever learned about them in the game, I’m only on Faro’s Tomb quest

He does, but we never know how. And he doesn't serm interested in them, and probably sees them as ignorant people, like every other tribe we know.

There could be huge power sturgles qith some of the larger trides like the carja or the oserm even more if apexs get overiden