There were 9 tracks from "if..." on Sound Collection. But yes, this will be the first full OST for if...
https://vgmdb.net/album/2482
Frankly, I just want the game to come out. It was ported to iOS and Android in Japan. SMT1 got localized (and I played it, and loved it!). But no one localized SMT2 or SMTif..., and that makes me a sad bear.