It’s difficult to find arthouse movies in their original language even in international Berlin. But if you look good, you will find screens. One of the better places is Central Kino in the Hackesche Höfe.
It is a neighbor of the legendary Eschschlorague bar. It features two small screens with the best arthouse has to offer. The screens are not very huge, but for blockbusters you still have to go to the Sony Center Original of course.