When taking the Warden’s Feedback trait to make focus skills reflect projectiles on a mesmer, the Temporal Curtain (Focus #4 skill) reflects projectiles as per trait description – sometimes.
I’ve seen many, many occurances where enemy projectiles simply fly straight over the curtain and damage their targets instead of being reflected back at the attacker. There seems to be some sort of vertical height limit on the curtain and if any projectile spawns or passes over it, they are unaffected.