Your answer should be accepted. The next time you see it, report it (click on the link at bottom left after you are marked wrong).
Working? As in being employed by Duolingo? In general the moderators of a course are doing this voluntarily, so they only get to work on issues when they have the time for it. I guess on the larger courses, like Spanish and German, they have employees doing research in order to improve quality. But most of the ones directly employed by Duolingo are engineers or designers.
Well, no one is working in this discussion forum - it's just us students helping each other, I'm afraid.
However, the course developers have made a huge effort recently and added reported alternative answers to masses of questions. They just haven't got round to this one yet, by the look of it. Patience is rewarded - keep reporting!
The correct answer given: "Do not come back at night" does not indicate where they are going back to (nyumbani). I think it should be "Do not come back home at night"
I think "tonight" is "leo usiku".
(Compare "this morning": "leo asubuhi".)
You don't need -eni for the plural? Is that because it's negative? How do you know it's a command? Is M- how you do negative plural commands?
1) Use the usual subject prefixes ("u-" sg., "m-" pl.)
2) Drop the tense marker (as for positive polite commands)
3) Add the negative marker “-si-”
4) If the verb end is “-a”, change it to “-e”
If the verb end is “-i” or “-u”, do not change it.
Usinunue! - You shouldn’t buy it! (you sg.)
Usichelewe! - Don’t be late/delay! (you sg.)
Msiondoke! - You shouldn’t leave! (you pl.)
Msisahau! - Don’t forget! (you pl.)
Msirudi! - Don’t return! (you pl.)
So, msirudi would be a command to multiple people? And Usirudi would be to just one person?
It seems like the prefixes for negative commands are the same as the prefixes for positive verbs (Ni=I, U=You (singular), Tu=We, ect.)
Also, in this particular sessions there is an instruction you should check. The suffix -eni is plural ending replacing the -a ending, or the -ni is the plural suffix replacing vowels i, e, o, u.
Should it be acceptable to start these plural srntences with "you all"? Or rather, would "you all do not come back home at night" be correct? If so it would really be helpful to distinguish between singular and plural with these commands.