It is a solved problem, Assimil or Michel Thomas (in person) have been making people conversational within a week of dedicated study. Plenty of language learners have reached C2 in 6+ languages including me. But it's not fun and certainly not appable (and these apps never offer anything beyond flashcards)"appable".
how does one get to conversational level in a week? I would love to know!currently anki-flashcarding my way through italian...