"We moeten ons haasten!"
Translation:We have to hurry!
I think that's a valid translation. In Dutch you can say "we moeten haast maken" although maybe it sounds slightly archaic
It is slightly archaic in English as well.
Just tried it upon coming across the question for the first time, and it's still not accepted. Come on, hasten is an English word!
There is a difference between "should" and "must": https://medium.com/@elleluna/the-crossroads-of-should-and-must-90c75eb7c5b0#.2mscdmj9f
Why not, "We should hurry!" I would use this sentence to mean must, need to, "we have to hurry!" in the right context can mean the same thing.
"should" is what others expect of us or what it would be better to do, but "must" is what is required.
I should do this, but maybe I won't. I must do this means I have no choice. It has to happen.
I agree that we often soften this when talking to other people. "We should" gives other people in our group the choice and people are often more willing to do something if we don't demand that they do it.