Sad news for Zen lineages! I suppose it could be argued that "it" CAN'T be "taught" only recognized. But then again, some how it is supposedly passed along . . .
What if it isn't so much the descriptive terminology that most readily leads one to this stuff, but the instructive circumstances created, and informative experiences shared, by talented and willing teachers that "can do" and "can teach" that are then coupled with (perhaps even previously known) descriptive vocabulary that best engenders understanding, learning, and the transference of knowledge and ability of this sort.
If this were the case, one might write pages and pages of both poetry and/or prose without fear of the "un-initiated" walking away with the "crown jewels," and, after all, those already "in the know" . . already know.
The only reason I feel descriptive terminology is important is that the brain tends to ignore information it can't categorize...
For example, I was working with a student at a seminar I taught. I was doing a slow Ikkyo and wanted him to feel the difference between when I had my attention "on the inside" and when it was "on the outside". As I held his arm I made the shift inside and then asked him if he'd felt it? He said, no he was sorry but he didn't. The funny thing was, his whole body moved slightly when I shifted. His body felt it but he didn't know what to call it so he didn't register consciously what I had done.
I did it again and told him to simply feel if anything felt different when I shifted, it didn't have to feel like anything he understood or could describe. At that point when I shifted he said yes, he could feel it that time. But I had to verbally prep him so that he could put his attention on it and register what was happening.
So much of what we do is mental yet my teacher never talked about it at all. He did things and I could feel he was doing something but I had no idea how to process what I felt. It's difficult to direct ones training towards acquiring certain specific skills if you don't know what they are.
No question, words alone are useless. That's why I don't worry when people tell me I should make the students figure it out on their own, that I am making it too easy on them. It doesn't matter how much explanation they get from me, if they don't train, they won't get it. They have to feel it from me and our other teachers frequently until it starts to become their own default setting. So there are no shortcuts. On the other hand I see no reason to let them get lost and wander in the wilderness either.