I don't see why this would surprise anyone. Star Trek, unlike Star Wars, has a dialog.... a LOT of dialog. It's very technically oriented and very English-centric. Unless they have a crack team of translators, 90% of any Star Trek film is going to sound like utter gibberish.
Sadly, this was one of the reasons for the reboot.... god knows all films have to be mega blockbusters that are so lacking in dialog and plot that any nationality can understand them.

That being said, the tv shows did exceptionally well in foreign markets from what I understand. It's just the films, which makes sense because TOS wasn't really released internationally so to foreign viewers there would be a bunch of random old guys in the films until Star Trek Generations.