Is it Kilala or Kirara
... It's amazing to see how many people don't know what they're talking about.
It's Kirara. It's spelled Kirara, and it's pronounced Kirara. There is no L in Japanese. The R, instead, makes the sound of both an L and an R. Hard to explain... you'd have to hear it to fully understand it.
It is not, nor should ever be spelled or pronounced Kilala. Like my name, which is Hari and not Hali.
So, bottom line for those who don't want to read all that:
Spelling: Kirara
Pronounciation: Kirara