Thanks @LTCTerry to get this straight. The piggyback FAA PPL states on the back of the card: issued on the basis of and valid only when accompanied by <country> pilot license No.XYZ. All limitations and restrictions on the <country> license apply = Inheritance of limitations and restrictions from foreign to FAA. Even if you pass your US BFR, you cannot execute privileges of your FAA PPL unless EASA current.