It is ridiculous not to accept "must" for the English translation.
I am now a contributor again and am hence able to check error reports. Your report says "repeat" instead of "respect", that's why it wasn't accepted.
I'm inclined to believe that's a bug. It's such an obvious translation.
'Need to' won't work. Why ?
We maintain the difference between "need to" and "have to / must" in the coursee.