Ways to talk about a mistake, error
Choose the way of translating this concept based on the meaning you're trying to get across, or use these as inspiration for creating your own way of expressing this concept.
dush dajun: bad plan
dush davaab: badly executed/implemented action
dush gaanader: to choose badly
(gaanader dush is fine in stand alone sentence, as long as no other words come after dush, so that what dush is modifying is clear)
dush nari: bad action
(Mandoa.ru contracts this to dunar, which is fine, because du is commonly seen in words that refer to something bad happening. Alternatively, use nar instead of nari.)
nari ures parjai: action without victory
(Alternatively, use nar instead of nari.)
nari ures bralov: action without success
(Alternatively, use nar instead of nari.)
ne'bralov: not-success, failure
ne'serim gaanader: to choose incorrectly
(gaanader ne'serim is fine in stand alone sentence, as long as no other words come after ne'serim, so that what ne'serim is modifying is clear.)
ne'serim nari: incorrect action
(Alternatively, use nar instead of nari.)
dajun meg trattok'o: plan that fails, plan that falls apart, plan that doesn't work
As another option, include ne'serim (incorrect) or dush (bad) in front of or behind — whichever is location less likely to be misunderstood as associated with another verb — a noun or verb to show that the modified word was not desired or did not have a positive outcome.