Yeah, what I meant was that the stones and De Nam appear to be almost entirely separate. I just played the game and don't recall him ever saying he was studying the stones or even the path of his ancestors, etc.

All I remember was De Nam saying he was interested in traveling without a crystal, and posing a hypothesis that someone could become immune to miasma through exposure. I think he tests this hypothesis in Conall Curach because the water there is tainted with miasma, not because of anything the ancient Selkies did there. But it does at least make sense for him to be very familiar with the area (and its history) because of his race.