Do you still have this problem? I solved a similar issue last night (after seeing your post) and - if you want - I can share the solution.
I am managing a journal on OJS whose main interface is in English. Papers are accepted either in English or in Italian (with a required translation of title and abstract); in the former case, only the English title/abstract have to appear, while in the latter I have to show both versions.
Here you can see what I mean: http://www.digitcult.it/index.php/dc/issue/view/6
And see also single-paper details…
Best.
Luca