I agree that we need an official clarification rfielder.
But in my humble opinion - if the removal of a knight from a city with the princess is the "move the wood" turn, you can’t place the phantom in the city. If you can place it at all, you have to place the phantom on another structure on the tile. As I se it, you have already used your first "move the wood" turn on the city and that excludes the placement of the phantom in the same city. In my mind this is the same as with the flyer and the portal. You can’t use a portal and a flying machine with both a follower and then a phantom.
I just checked the IOS Carcassonne. There the use of the princess excludes the use of the phantom too. I don't know how involved Hans im Glück have been in the game, but they have approved it.
Maybe not so important - but this concerns the shepherd too. The adding of another sheep or scoring your flock always follows the "move the wood" turn. So what do you do when the princess (and you use it) adds to the farm where you have your Shepherd?