meh, language learning has an inconvenient truth: sometimes it’s just rote memorization. it's the reflexive belief that every human endeavor must have a hidden optimization waiting to be discovered. Language learning is one of those domains that stubbornly replies, "Cool flowchart. Now memorize 500 words and spend 200 hours listening."

There’s no clever engineer hack that replaces time spent with the language. and with regard to japanese, please stay away from romaji, unless you're still in beginner stage and typing things out to communicate words you already know the phonetics to.