Ardent, transparent, illustrious
The name Kiara is latin and means 'bright, clear, famous'
A little swarthy match-seller
However, Kiara is also an irish name meaning 'swarthy' or 'little dark one'.
The Little Match-Seller is a fairytale by H.C. Andersen about a little girl, so there is also a gender reference.
with bare head and naked feet,
Kiara is an equine and thus has a 'bare head', ie. no horn. Species reference.
luck may lie in a pin.
Fluff, name of another H.C. Andersen story
An old mansion with thick, red walls.
The keyword here is red, a color reference.
“I know every stone of it,” says the wind.
She is close with Breeze, he knows her very well, thus a relationship reference.
They were a rich, noble family,
Fluff
born in affluence and nurtured in luxury,
More fluff, but also ironic since Kiara had a pretty effed up childhood.
feasting on trout and goblets of wined.
Trout is a spotted fish, so this is a breed reference, as Kiara is an appaloosa.
Also, wined is another color reference
Jittery, glittery, shivery,
Jittery is a synonym for nervous, so this is a personality reference,
as well as shivery, because she tends to be just that around stallions.
my authentic delivery.
Authentic is a synonym with faithful, so this is another personality reference.