I would like for DL to show a "canonical" answer (which i take to be the one displayed when you open the sentence discussion page) after you entered your own translation of a sentence.
Currently, you only get gentle corrections of the sentence you wrote, which seem to try to keep as much of it the same as possible. But even if your translation is technically correct, there is often a much better way to express the meaning of the prompt.
This is actually the main reason for me to open the discussion page whenever i'm not perfectly sure of myself, but it would fit nicely in the green (or red :)) banner.
Rarely i've also seen "Another way to translate this:" messages, i guess i just want more of those whenever my translation differs from the best one.
It was like that in the past.
At some point in the past, Duo would show you the "canonical" answer as soon as you didn't answer said canonical answer and, if you were answering an incorrect answer, it would show you in addition to the canonical a correct answer "close to yours".
For some reason (probably due to some A/B tests showing it had globally, statistically on all users, a bad effect on users' learning) they stop that.
Since they had it then stopped it, I unfortunately(*) see it as highly unlikely they put it back.
(*) I found the old behaviour far better, personally.
I seem to have observed that these sentences are often used as new prompts in the other direction immediately after my submission of the sentence. There have been several times already when I thought: "Oh, that's almost the same sentence as I just wrote -- and this one is better than mine."
I don't know if that's the feature or just my accidental observation.
Edit: There's the additional problem that often there is not "the one" correct answer. There may be several ways of translating a sentence which are equally valid and common, with their use only differing in specific contexts or according to someone's taste.
I think we increase our ability to assess sentences the more we deal with them, compare them and think about them. That's why I like to click the "discussions" open, to see the various points of view and work on my own opinion.