Partial, tentative answer:
The clues look like
cryptic clues.
I got the third line, and I got most of the rest by guessing the theme.
It starts with the number 6, then the 15th, and ½ of a band on the arm but, it’s for your foot.
Number 6 is VI (in Roman numerals), the 15th (letter) is O, a band on the arm is a bracelet, half of it is let (well, it's only 3/8 not half). It gives the answer Violet, and I'm not sure what to do with "it's for your foot". Edit: a band for the foot is an anklet, so this gives a better way of getting let as half of the word. (Credit to M Oehm and fljx in comments)
With the start of spring, comes the end of fun where The Bat's home becomes just a name.
Start of spring is S, end of fun is UN, and I'm guessing The Bat's home is NY (New York), but I don't know why.
When, in the uppercase of Malaysia, a short way to say a pirate’s treasure is, an A in elementary.
Uppercase means capital, capital of Malaysia is Kuala Lumpur or KL. I'm guessing the rest makes AUS but I don't know why. Edit: a pirate's treasure is gold, a short way to say that is Au (its chemical symbol). (Credit to PDT in comment). And the final S maybe comes from a short way to say "is".
So we get
Sunny, Klaus and Violet Baudelaire, the main characters of A Series of Unfortunate Events. Which is also confirmed by the title ("no happy endings").