This is a common misconception.
The Polynesian is an extension of Adventureland and was designed as a love letter to the post-war Tiki culture of the 40s and 50s. There's some nods from the French Polynesian, like the concept of the Great Ceremonial House with the outer longhouses, the previous lobby water garden, now the bungalows, etc. However, I don't think WDI ever intended it to be authentic, just like Adventureland is not authentic.
I wouldn't consider Frontierland, New Orleans Square (
Disneyland) or Liberty Square authentic representations of those regions either.
Aulani is supposed to have taken actual culture nods from Hawaiian culture.