Grammar and Spelling check
I have just translated a sentence and when I clicked on "Best Translation", I found that "schwamm" has been translated as "swum". Either the translator has confused the past participle with the past tense or this is a spelling error. Either way, this cannot be the "Best translation".Is no check made on the grammar and spelling of the translations?
Schwimmen. Ich schwimme, du schwimmst, ... (Präsens). Ich schwamm, du schwammst, ... (Imperfekt). Ich bin geschwommen, du bist geschwommen, ... (Perfekt). Der Schwamm - the sponge or fungus (for example in wood).
I'm pretty sure "best translation" isn't decided by someone at Duolingo-- it's the translation with the highest rating by users on the site. That means there's a lot of room for error.
The highest rating does not necessarily mean that the translation is grammatically correct or even make sense. In that case, I don't see how Duolingo can match professional translators! This could be a big bug.
Theoretically and statistically the right answers should get the most votes, but in actual life I am not so optimistic. There is a lot of grotesque nonsense considered to be the best translation.