I suspect people have been noticing microexpressions in others for thousands of years, but have been unable to articulate what specifically they were noticing because they're too short to reach conscious attention as anything besides an impression of the other person's emotional state. (Unless I'm misremembering Ekman, he's come across people who were able to notice them without taking any training from him beforehand.)

Microexpressions are not the only thing that's outside of conscious attention that gives us information about the feelings of another person.

It's worthwhile to be able to distinguish different ways and label them.

But it does seem to me that you can minimize the number of hidden inferential leaps by making as many as possible explicit, and that with a narrow enough focus, a specific curriculum for that issue could be developed

Even if it's possible to build a specific curriculum that teaches a certain skill, that doesn't mean that it teaches the skill faster than a month.

Just as you can't get a sixpack in a week, changing substantial things about your mental landscape might also take time.