This is a little question of the origin of the Sylvari's Celtic, mostly Welsh, based culture: where does it come from, the names especially? The Sylvari haven't had the centuries and millennia to develop the unique aspects of their culture, like social norms and in particular the style of naming, so where did they or the Pale Tree come up with these specific aspects of their society?
We know why from a design stand point, the Sylvari are meant to be that 'Fae' race and what better IRL culture to base a Fae race off of than the people that created the concept: the Celts. Early concepts of the Sylvari were even called Sidhe, which is a Gaelic Celtic equivalent for faeries and elves. The separation of the Tablet Sylvari from the Nightmare court is pretty analogous to the Seelie and Unseelie courts of the Celtic fair folk. As for the heavily Welsh focus, particularly on names, Anet wanted the Sylvari to also have that Arthurian chivalry as a pervasive aspect of their character, and as I recall a decent amount of the King Arthur legend has its origin in very old Brythonic Celtic lore it makes sense to go with the Brythonic culture of Wales.
But how in universe did the Sylvari pick up this culture, the naming conventions and the Arthurian chivalry, etc.? The story show their society to be almost a 'tabula rasa' especially in the near lack of gender norms, but not with these other aspects. I would suppose that to some degree some of the knightly chivalry could be derived from the Tablet, though I do question whether it would cover all of it. But what about the naming style, where did they get it? Where did the Pale Tree get it? While Ronan is a Celtic name he's only one person, Ventari to the best of my knowledge isn't a Celtic name, nor are the names of the others seen at the young Pale Tree in EotN (Plus Ronan is a Gaelic name, not a Brythonic one, though that probably doesn't matter, we're talking about a Tyrian equivalent to Celtic culture, not the real world one). Its very questionable that the Pale Tree could have gotten an entire cultures worth of naming styles and other cultural conventions from just one person.
So what could be the source of the Sylvari's Celtic culture? My best guess would fit into my general theory of the nature of the Sylvari themselves; that there is something more to them having become more than the soulless and will-less dragon minions they were meant to be than a pacifistic human and centaur somehow raising the Pale Tree to not be a dragon corrupted minion factory. Some greater force, an X-factor that changed the equation and as such changed the very nature of the Pale Tree and the Sylvari. And that change would also include the bits of Celtic culture the Sylvari have today.
But what do you lore-hounds think? Feel free to let me know what I might have missed or what's wrong with my little theory, I'm sure I mixed something up in that wall of text above.
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