You're reading too much into it. The technologically advanced, ancient, vanished race is a fantasy cliche. I remember it being part of several SEGA (Phantasy Star) and SNES games. What's more, the Elder Scrolls actually predates Suikoden II by a few years, and that was the first appearance of the Sindar, I think. They might have been mentioned in passing or in an old book in the original game, but you didn't explore their ruins or anything. I think the Dwemer legends first appear in Redguard, which came out around the same time as Suikoden II. If they were mentioned in Daggerfall or Arena, they could even predate the original Suikoden.