Ahh yeah, Easter comes so early this year that I didn't even realize it is already in March. In this case I guess you're stuck with the train then.

One possible option would be to fly to Kuopio airport (KUO), some 110 km away from Joensuu. Schedules could be a little better, since it's serviced by a greater number of flights daily (and by KF as well). Transport between these would require some combination of busses (or a rental car) and given that at Easter time that could be quite problematic as well, so I don't know if it's viable or not for your case.