Barrage + Rain of Arrows not working together

See title. Is Barrage not supposed to work with Rain of Arrows even though its a bow skill? Its not consuming the barrage charge and not getting more arrows.

Yeah I am confused by this skill. I am playing a poison pathfinder and it doesn't work with Vine Arrow, Toxic Growth or Freezing Salvo. It works with Poison Burst Arrow so wonder if it only works with the projectile type skills? If so the tool tip is unclear.

I also don't understand how to accumulate more Frenzy Charges, they don't appear to be mentioned on any other Ranger skill I have seen?! As such I only get the minimum of 1 extra Poison Burst Arrow Projectile. As Barrage is more mana to cast this seems completely pointless?!