Forge version: 1.16.5 - 36.1.65
Psi version: Psi+1.16-95

I set the Position to [Caster Pos + Y:16] and Target to projectiles.
I would expect Closest to Point to only be able to locate arrows above my head. Instead, provided the position isn't set to >32 block away from the caster's pos, it finds arrows in a 16r sphere, centered around the caster.

Here's a spell
Fire an arrow, move less than 32 blocks away, and you'll still be able to locate it.

This makes filtering out a non-airborne arrow difficult.