For most cruiselines, for fares that are specific to residents of a certain country, the cruiseline will require proof that you qualify for that rate. Even if you somehow manage to book it, you could be asked for proof of qualification at the pier and if you don't have it, could be 1) made to pay the difference in fares or 2) denied boarding.

You can try contacting a Swedish travel agent, but do not misrepresent that you are a resident of Sweden if you aren't, in order to get the fare.