"Would you like to order?"
"You" can be a singular 你. "Would like" also translates to 想. A question can also be expressed with 吗. And all combinations of these. Duolingo should accept all correct translations even when they are not idiomatic, but it would be fantastic if an alternative more idiomatic translation can be suggested in these cases, for all languages.
I have a little different thought.
When we say "would you like..." we are saying "do you want..." plus a certain degree of politeness, which is also an essential component in communication. "你们要不要点菜?" is direct and blunt. If a waiter come to my table and say this, I will certainly frown at him.
So personally I would expect a translation that is of comparable utility to the English sentence.
This kind of problem is quite obvious in the Japanese course as a higher degree of attention to the social context is required.
I agree with your idea that it would be great if all correct translations were accepted but a more ideal / alternative idiomatic translation given as part of the confirmation.
Sometimes I wonder if there would be a better way to put the answer. ‘Yes but this is even better’ would be a nice bit of feedback when learning.
I believe the character for "ma" as a question marker word is 吗 rather than 马. Otherwise your sentence with that correction should work, since 要不要 and 要...吗 are supposed to both be correct ways of asking yes/no questions. DL still rejects it though as of Apr 2018, which I've reported.
I think this question (especially from English into 中文) hasn’t been updated with alternative translations yet (mid-May 2018). I’m reporting them as they come up (‘you’ can be singular, 要不要 is not the only question form for this and perhaps not the best, etc). If you’re confident of your answer being right, please report it too.
Many of the other questions in this Duo have improved hugely so it looks as though they’re getting there.
It's ridiculous that it only accepts 你们要不要点菜？as the answer. I tried multiple equivalent translations for the English sentence, such as 你们想点菜吗？你们要点菜吗？and even 你要不要点菜？but nothing else works. This needs to be fixed. I've relied on Duolingo a lot for language learning and find it's incredibly useful, but there's no excuse for this. Makes me rather upset that I paid to become a Plus member.