Disingenuous é um adjetivo da língua inglesa definido como:
Someone who is disingenuous is slightly dishonest and insincere in what they say.
[formal] e.g. It would be disingenuous to claim that this is great art.
Synonyms: dishonest, cunning, sly, designing. from Collins
Usage Note from The Free Dictionary: Disingenuous means "not ingenuous," that is, not innocent, naive, or guileless. As such it can refer to someone who is insincere or calculating, as in It is both insensitive and disingenuous for the White House to describe its aid package and the proposal to eliminate the federal payment as "tough love," or to someone who is pretending to be unsophisticated, as in "I don't have a clue about late Beethoven!" he said. The remark seemed disingenuous, coming from one of the world's foremost concert pianists. Both of these examples were accepted by 90 percent of the Usage Panel in our 2016 survey.
Diante das definições acima, dependendo do contexto, "disingenuous" poderá ser traduzido pelos adjetivos "falso", "dissimulado", "fingido", sonso ou até mesmo "hipócrita".