Comment 2 for bug 488120

a) It is possible that Inkscape picks up the language that is set in the 'System Preferences > International > Language' as 'Order for sorted lists'. Can you test if any changes you make there has an influence (after restarting Inkscape, or - better - logging out and logging back in again)?
b) is 'Greek' anywhere in the list of preferred languages for the menus etc. on the left side of the same preferences panel (International > Language)? If it is, and you don't need it every day - does it help if you temporarily remove it from the displayed list (the language files are not deleted, you can add it back to the list again later) or move it further down?
c) Are there other user accounts on your mac which you could test whether they have the same issue?