Kingdom of Knuffel

Yeah, she might not call them auras but that's pretty much what she's seeing... or the natural magic of people. White for divine, copper around peoples' hands and hearts for the wild-magic, the individual colors of human mages...

Pretty sure it's not any kind of form of synesthesia.

No, no, only with animals
The only time she sees mists and glimmers and such is when Numiar uses a spell and works it through her so she can see it. The Gift is a white mist via said spell. Wild magic is copper fire inside one's veins, and that's all she retains from that spell

Of course, when someone uses the Gift, there's a color, and everyone, Gifted or not, can see it. Jonathan is blue. Alanna and her late twin, purple. Numair's is black. There's also been mentions of red and brown
Gods get white fire. Gold, as I said, for immortals, such as unicorns, centaurs, hurroks, Stormwings, spiderns, etc. And natural animals, only a bear is mentioned as brown, because it was rabid. Black and red spots, very sick

Yeah, she mentioned that when talking to Jonathan, right? Blast, must re-read these books. It's been too long and the details are all blurring together...

Yeah, it's mentioned when talking to him shortly after arriving in Tortall

The Immortals quartet
Tho if you want to understand the Tortall universe better, you'll want to start with Song of the Lioness quartet
SotL, Immortals, Protector of the Small quartet, and then the Trickster duo for those that are in order. There's also the Beka Cooper trio, which is set 200 years before the others, Young Warriors mentions the Shang Unicorn, there's one on the myths of Tortall, and then the rest I either don't have and thus don't know if they're Tortall or Emelan, aren't out yet, or are set in Emelan

They're by Tamora Pierce

I like your friend already ovo

She's not big big, like Harry Potter, or Hunger Games, or twilight
So I kind of expect people to not know of her
I follow her Tumblr and boy do the Q&As have a lot of interesting stuff