It couldn't have been made like that. I've got one of those in the shed and the hole goes right through. The ISCV won't work without being able to draw in any air. I've never seen one with a pipe stub but no hole.

There is a different type of EFI duct for the inner wing mounted ISCV. - in this case the ISCV draws its air directly from the air filter - where you have that hose with the white thing jammed in it.

If the plastic duct of the plenum is genuinely blocked then don't drill it out. Instead, unblock that other pipe on the air box and connect the iscv to that. It should then function correctly.

Sounds like your car's air system is made up from a mish-mash of bits of other cars...