I don't really like the Nirvana label. It's pretty arbitrary, considering some Hong Kong ponies are considered Nirvanas (Raindrop, NSS Cupcake, alternate Birthflowers) while others aren't, even if they weren't sold in the US (Hopscotch, Baby Applejack, NSS Shady).
I think it makes more sense to talk about variants.
Anyway, I'm getting off topic. Those little figures are SO cute! I love Applejack's dynamic pose!