Translation:We saw a wide river in front of us.
Native UK English speaker here! There is definitely a meaning of "before" that literally means "in front of", though it may be slightly archaic. If "we saw a wide river before us" isn't accepted as a valid answer then I think it should be. However, I assume the form "We saw before us a wide river" is getting rejected for the same reason as "We saw in front of us a wide river" e.g. presumably someone doesn't accept that it sounds natural enough to an English speaker, and/or thinks it's too much of a word-for-word translation?