I often used to monitor the LBA Airbands when the Adria/Tarom 1-11 was approaching and I don't remember any language difficulties at all. The pilots spoke English with a distinctive Eastern European accent but were every bit as clear as the Wardair 747 pilots who used to arrive at LBA at much the same time on Monday morning. On the other hand, Tarom had only to satisfy the Yugoslav authorities of their aviation English competence, not the CAA.