Because the sentence with that word has not been added as an alternative translation for this Hungarian sentence yet.
Report the missing translation if it marks you wrong for using "cunning". (And be prepared for a wait of a few months before the alternative is added; there's a huge backlog.)
The suffix -ba/-be means that you're entering something. English is a bit lazy in that regard: if you're going "to" the city, you're actually going "into" it. Same with "to the room" or "to the zoo".
Just going "to" something without entering it is expressed with the suffix -hoz/-hez/-höz: "A ravasz rókák a kerthez ugranak."