Sorry if this have already been answered, but how is "target empire" defined? It is obvious in some occations, but not others.
For example, in an event? "Target empire loses all money." Must that empire be in range to one of your empires? What if the event was played without playing the Action card on any empire?
In my opinion, "target empire" simply means the empire you choose to affect. Is that correct?
That is mostly correct. Note that not all cards target an empire as such.
Range restiction applies to an artifact or event if it is an assassination event, if the optional"take that" rule is in use, or if the wording or the card calls for it.
I reccomend checking Daniel Peters' Nitpickers Guide (2.1). While it is unofficial, and does not specifically define 'target empire' or 'target', it does clarify what counts as a target for what artifact/event for what purpose.