Re: Update
It's really up to you. On the one hand, the rolls were made and the consequences should occur. On the other hand, banking rolls like this means that the player has a guaranteed hit/miss on their next action, and will plan their tactics accordingly. Personally, that seems more meta-y than discarding the rolls for an attack that, due to outside circumstances, did not occur; then the player has the same uncertainty about the next attack as they would about all of their attacks.
But anyway, Neya hangs back. Regardless of the attack's result, a strike at this instant is counterproductive. A better play is to wait until next round, sandblast Hastur, then have Neya pull Kaele to safety while Hastur is distracted by the sand and barbarian in his face.