I don't have a primary source to confirm this, but I'd be very surprised if the chwinga wasn't based at least in part on the kodama.
A nature spirit that lives within trees
Chwingas have a feature called Natural Shelter that allows them to live within trees and other natural features.
Kodama (木霊, 木魂 or 木魅) are spirits in Japanese folklore that inhabit trees, similar to the dryads of Greek mythology.
No shared language with humans
Chwingas have no language with which to communicate. The sounds typically attributed to kodama are echoing natural sounds, rather than speech.
Occasional fascination with humans
In some cases, a chwinga
might simply like the way a humanoid walks or the
way it combs its hair. Other times, it might be smitten
by a humanoid's ability to play music or to eat copious
amounts of food.
Kodama are known to take on the appearance of humans, and stories exist of them even falling in love with humans.
Chwingas have numerous abilities which which to make themselves unseen: between Natural Shelter, pass without trace, and +7 Stealth, they aren't seen unless they want to be.
Similarly, kodama are rarely seen, to the extent that a tree in which one lives is referred to as a kodama as well.
Depicted in media as a tiny humanoid with a white, mask-like face
ToA describes chwingas as appearing like animated dolls, and minus the black skin and hair, in the illustration they bear a striking resemblance to the kodama in Princess Mononoke: