So one also needs to spend a couple of days doing a standalone FAA PPL.
One does need not to do a standalone PPL. In fact as I understand it you can't add a foreign instrument test passed to a full PPL, you have to do an FAA IR.
For those with a JAA IR who just want the foreign instrument privilege you get a piggy back and take the FIP test.
We have to accept the fact that if you want to fly on another countries register and rules outside of that nation you are going to be faced with an element of inconvenience. If you don't like the inconvenience you operate under your own national regime.