I don't know of we know which pack is being refreshed but like I honestly don't get why anyone would think it is Spa Day when the pack is literally perfect. It doesn't feel like a stuff pack at all and it is not buggy at all either.
The only thing that I can think of could be added is that our sims could be the yoga teachers or masseus' when they hit level 10 in the wellness skill though that is not really essential for me to have that in my game.