I have not read all the posts, but just wanted to add this comment. I trained in Aikido in Japan for over ten years my Japanese was rubbish and is still rubbish as I found many people in Tokyo speak reasonable English. The point is: in some ways not speaking Japanese in Japan when learning Aikido is an advantage as you have to pay a lot more attention in class and very carefully watch what the teacher id doing. You can not learn Aikido by talking about it in any language.
In the days when humanoids hadn't developed language, Thag's son learned how to throw a spear by watching Thag throw a spear, and then practicing.
Or - so it must have happened. No video, no lecture hall, no youtube.
More recently, the lectures we had in "how people learn" during PE undergrad studies showed that people pay more attention to demonstration by "significant peer" than by "instructor" or "expert performer" I think the contrast is "instructor" is an expert, perhaps, but he's been doing this for a really long time and I find this difficult... An "expert performer" - well, they're making it look so easy - I'll never be that good. (Neither of these interpretations include the number of years that the instructor or EP spent learning the movement.) However, a "significant peer" who's usually a person of similar age who may have only recently learned the movement gets the reaction "Hey, he (or she) can do it, I bet I can do that too - let's see, the left hand was here, the... right foot did this, the body was positioned here" but all in non-verbal internal dialogue where the person is imagining his/her body doing the movement...
"monkey see, monkey do..."