Since Kaya was introduced to the AG historical line in Fall 2002, I've owned three dolls. And I've never had any problems with their hair.
My current Kaya (which you'll see pictures of in a moment) was bought off the Bay in Spring 2010. Given her skin coloring (the first release Kaya dolls where darker) I think she's a few years past 02. She was owned by an adult collector who never did anything with her. So when I got her, her hair was mint. Still braided and had never been touched.
Sweet! A blank slate. In the years since 2010 I've moved twice and had to pack my AG belongings away. That resulted in a bit dusty and in need of fixing Kaya hair. By the way braid spray (thanks to Neth of AG Outsider) works wonders. For this Kaya I simply washed her hair in Sauve conditioner and let it air dry. Before combing it out with my fingers and the AG purple hair pick.
It upsets me when I read about collectors crabbing that Kaya (or Addy,Josefina,Cecile or any of the other non white dolls) has hair that's difficult to manage. Because it's not true. What it takes is stepping outside your comfort zone and understanding that not every doll (or person) has the same hair type. I.e. white.
I say that because Kaya has my hair, I'm half Cherokee (Wild Potato and Wind clans). And for most of my life it has been the source of fear, anger, and put downs. Things that many non white and non Native folks wouldn't understand.
But here's the thing. If I had Kaya as a kid, it would have helped and I'd have been proud of her hair. As I am now. It's not a thing to chop off, try to straighten or leave pristine and mint in box braids.
Hair is very important to Native/First Nations folks, for various reasons. Mine is being grown out, showing that I'm keeping to an old tradition. And you bet I'm dang proud to be doing it. A tradation that was around when Kaya was growing up in 1764.