On the other hand I doubt that people two hundred years ago had a concept of microexpressions that only take 50ms. We only know about them because we have cameras.

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.)

It's not clear to me that you can always short circuit that month by providing a different explanation.

To say it's always possible would require an impossibility proof for obstacles, so I won't attempt that. 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, and the spiritual teacher's problem is that they don't have the time / narrow enough focus to develop a curriculum for every issue.