[plugin request] right click detection

Plugins Plugin Requests
2

I guess you want to trigger a command block and thus executing a command.
I am not aware of any tricks that could achieve this with vanilla scoreboard and command blocks magic.

Though I can recommend you to look into Kt-Skript.

Something like

onBlockRightClick {
  if (causedByPlayer && clickedInAir && causingPlayer.hasItemInHand()) {
    val heldItemStack = causingPlayer.getItemInHand()
    if (heldItemStack.type == ItemTypes.FEATHER) {
      Server.console.executeCommand("say Right clicked in air with feather")
    }
  }
}

could work for you.