[Gandalf Parker]

No it will only target provinces you own. You can check that when you start the spell and it makes its recommendation. But sometimes the sequence of events can change the ownership in that same turn which can give you an answer for a province you no longer own.

Its kindof irritating to see a message on your site search saying it found 3 sites but the flag shown on the message is now someone elses and you cant see what sites you found. (unless you are sieging a castle).

But it does make some game-reality sense. The province targeted for that turn shows can be viewed before you hit END (by hovering the mouse over the mage and seeing the message at the bottom of the screen). When you hit end, the game hosts and decides all events. The Mage sitting at his lab doesnt do a new check just before casting so sometimes he continues to cast on a province that you already lost.