The Vistani come from Ravenloft. If you are ripping of Dracula or Eastern Europe for Gothic horror, you need gypsies. Ah, the Tarokka deck; did you know this year it is 20 years old? I have a deck, and looking at the back of the cards I saw that 1992, and just blinked.
Anyway, a “tradition” is different from a grimore and an overlay template; it is a pool of talents that have restrictions on who can take them that, together, represent a body of lore among an oppressed and marginalized people. (It is no more complicated than that.)
One of my design principles in working with templates is I expect about a 60/40 utility, sometimes creeping to 70/30–I expect the DM to get 60-70 utility, and players 30-40. Sure, these are all fun to play; but there are only so many players, and the DM has infinite NPCs. While these make great protagonists, they also make great enemies and obstacles and allies and background color.
Bearing that in mind, if you read this and don’t start dreaming up lots and lots of plots fueled by this set of talents, I don’t know that I can help you…