Easyjet has dropped Berlin to Tallinn
Well, I used to travel with EZY from Tallinn to SXF on several occasions (Tallinn is just a couple of hours from Helsinki by ferry). Pretty good load factors every time. It's just that EZY more eagerly try to maximize returns and at a time didn't achieve fares good enough on this route. FR calculations allow for more patience, I guess.
Cheap rail ticket from Baltic countries to Germany? Pure abstraction. I've once tried to get through Baltic countries by rail. I'll not attempt to do it any more, believe me. Besides, the international rail tickets are pretty expensive in the region.
Apart for Lithuanians travelling to Berlin, I would also find several reasons for Germans to visit Lithuania, some pretty amazing historical sites there.