Remove translations that we have already completed
I think that duolingo should remove the translations from the "top documents" and "recently added" tab that are in the "your translations" tab. I find that to click on a document that you have already translated that is in those categories is somewhat annoying, and a small waste of my time. Duolingo could easily fix this problem with a small amount of work, I think, which allow it to waste a few less seconds for each user.
However, if some users want their translations to still be in these categories, the developers could simply add a checkbox to the user preferences page that says "remove completed translations from the two left tabs" or something of that nature.