Research says that grammar should come later. Grammar is easy to teach and grade though, while more effective learning methods don't show any results as fast, but in the long run do better.

Comprehensible input is key to learning a language. Grammar is helpful only after you are getting to where you could almost guess those rules.

I can see that being the case for learning how to speak a language, but I'd rather first learn how to read and write the language. And mapping the foreign language's rules of grammar to those of my native language feels like the best way to start that.

“Mapping grammar” is inapplicable in many language pairs. Especially English which is so simple.

How will you map t-v distinction in romance and Slavic languages to English? Or Russian and German cases? Or French’s plus-que-parfait? Or English’s question order to Russian’s flexibility in word order?

This is without even getting into the more removed languages…

Noun signal, adverb, adverb, verb, verb, verb, plural noun, sentence end signal. Personal noun, verb contraction, verb, noun signal, noun, verb, personal noun, verb, compound noun, join signal, join signal, verb, personal noun, verb, verb, verb, noun, verb, noun.

I'll bet you didn't catch a thing from that. Now granted I haven't done this since in decades so I probably got a lot wrong, but even if someone corrects it you wouldn't understand anything.

Here is what I wrote: 'The best way is to map words. You don't need the grammar until you understand something, and then you will figure out grammar from context.'

Research and people who actually learn languages both agree that you need lots of input to understand the language. Grammar is useful, but only as a small percent of study.

Well, I was expecting that mapping the rules of grammar would comprise more than just assigning part of speech tags.