Nay, Sylphy's boobs aren't nerfed. It just blended with the wind.
(I'm at ch25 when leaving this comment, and that is a joke.)
EDIT:
I am putting this manga on hold at Ch60.
Its good since its supposed to be fluffy and healing.
But, I can't ignore the fact that the 25-year old protagonist I.Q. is TOTALLY lacking, not to mention he thought he is better than the "involved-great-water-spirit" in that matter just hurts my head.
Tough I've tried not to think about it, each time when he commented about her. Sadly, I can't. Its just 'birds of a same feather flocks together' all over again to me.