Reading/newspaper vocabulary and grammar != spoken vocabulary and grammar; at times, they are two different languagesに違いない. As Google search declares, WK is a Kanji Learning Application. Using it to learn conversational vocabulary, and then complaining that it doesn’t work…well, that doesn’t make sense; perhaps you just misunderstood what WK is for.
I’m one of the few students in our training center using WK for kanji acquisition (vs internally-provided materials and methods). Today, thanks to WK, I could read the paragraph below, because WK had taught me 乾い, 枯渇 and 潤, which are kanji/vocab ‘we don’t use’, whereas my classmates had no idea what the writer was trying to convey.