So last answer was deemed wrong because I didn't include "You all" in the command for a -eni verb, which would never be used by a British English speaker as the plural is implied by context. So I add you all to this "you all buy mangoes" - which to be honest seems wrong anyway as it's the same as the present tense and that is now wrong. It's very inconsistent.
There was a big debate early on whether there should be something in the English sentence to mark whether it was plural. As some people did habitually use 'you all' it was eventually sort of accepted, but was never fully implemented as the team at the time were busy doing non-Duo things that took priority.