An idea for encouraging people to rate translations.

[amichail]

When you enter a translation, Duolingo could show you the k closest translations by others to what you wrote. You would then be asked to select the best translation among the k+1. I think people might like this since it allows them to see quickly how they could improve their translation — possibly even improving their command of the language they already know in the process.

[monzac]

Isn't something like this already in place? I'm sure I've seen translations for rating change when I have edited my own versions.