I don't think there were any translation problems of Czech movies really. And I know there were great movie makers in Czechoslovakia and in most of communist countries too. But I think there could be the availability problems with more ambitious movies. I imagine the first step was always the censorship in the country of origin - many good films in our countries were left on shelves without the censorship acceptance. Some of them were ridiculously cut before showing to the public. The rest had to wait for better times. Now imagine that a country wants to export its movie to show them abroad (in the other country of the communist block). They know it has to undergo the censorship in the other country too. So if they allow it and the others reject - it would be shame. You can imagine: "Are you crazy comrades? What are you trying to send us? It's potentially poisonous to the working class!"
So that's why I think the foreign movies we were allowed to watch were thoroughly checked against any lack of ideological correctness.
The other problem was, that the communism was different in our countries. In Poland we always had a little bit of freedom (going to church, possessing small parts of land, making movies that laughed at some aspects of life in our country), but our economical status was very low. The shops were empty. When a luxury article (e.g. toilet paper or meat) appeared, long queues were formed in front of the shop.
I was happy to travel to Czechoslovakia, Hungary and other countries then and I was surprised seeing things like chocolate, coffee, orange juice, ham, and other luxury goods there. We could buy it there and eat, but it was very hard to smuggle even small quantities to our country. It could be a reason some of us had problems with understanding the type of humour of our neighbours. We were laughing at different things.