Well, for the point difference: if you look at the spending tables then you'll see that SAS used the classic StarAlliance award chart, which means 60% of a round trip in points (or 42000 points for economy) for your one way trip. Aeroplan has a different spending table, in which it divides Europe in Zone 1 and 2. And with Aeroplan you only need 50% of a round trip for a single trip, which in this case is 30.000 points. See this link: https://www3.aeroplan.com/FlightRewardChart.do

For the costs... that's where it gets a bit shady. From personal experience I can say that things seem quite depending on agreements between airlines, availability of award seats and even the competences of the agent on the phone. SAS is not allowed to have weird surcharges on its own flights, but that doesn't say much about what it can bill when booking with other airlines via SAS. I have paid everything between $50 and $800 (conversion rate at time of booking) for award flights within StarAlliance.

I dare you to use your SAS points for a StarAlliance reward flight with Lufthansa next time. I bet you'll throw your phone out of the window when you hear the total costs.

Anyway, please check your award ticket and see if it's fully refundable. If so, you may try to call again to SAS and try to book the same award flight again. If the international surcharge pops up again, interrogate the phone agent about it and find out where it comes from. There's probably not much you can do about it, but at least you'll get to know what it is.