Let me try to explain a bit about the Potlatch thing:
The Potlatch is the defining element of the Salish culture. When the Potlatch was banned in Canada for a number of years (it was only made legal again very recently,) it did terrible things to the Salish people, who had pretty much just had their identity banned.
What is a Potlatch? Well, I wouldn't take my word for it, you can look it up, but here's the easy version:
In Salish culture, there are nobles, non-nobles, and slaves. Nobles are pretty much just the "rich class" but it's a bit more complicated. You became a noble because you were rich and nobles could also own slaves and other people couldn't. Now, by "rich" I mean many forms of wealth: money, slaves, land, houses, and even non-material things, like names or songs were wealth.
Now, influence and power were not seen as being the same thing as wealth. In fact, a person who was powerful would want to ritually prove that their wealth did not make them great. So, they would have feasts in which they would actually give away or destroy their wealth in order to gain influence. A noble would often destroy money, or kill slaves, or give his family name away to some other family, and the more he gave, the greater he was in the eyes of his people and those around him (which often resulted in a huge amount of monetary loss for the Potlatch host.) Even more so, it would create an obligation of more generosity/destruction from those who he gave gifts to, since one would not want it to be said that his own power was due to the gifts given him by someone else.
(Aside note: in the past, the Canadian government banned Potlatches because they didn't like it when people burned large amounts legal tender. It messes with your ability to track circulation.)
(Other aside note: the popular use of the phrase "Potluck" comes from Potlatch, meaning a meal where everyone brings food and "gives it away," as opposed to the original English term "Potluck" which is to go somewhere to eat food when you have no idea what the food is going to be.)
So, from a design perspective, the Salish need to have a UA based on the Potlatch. What that UA does mechanically is certainly up for debate and will probably change as time goes on, but the current design is meant to closely reflect the Potlatch tradition and any new version should also work that way.
Growth, 
Production, or 
Gold bonuses during a Golden Age. However, the 
Culture boost is increased to 75%, a randomly-selected Unique Unit from a Civ not in the game appears in the 
Capital, and City-State Influence cannot decay. 
Tourism when garrisoned."
