I have a day of meetings today, so cannot come back in detail with the points you made. I will clarify just one point.
Ernesto Lemke wrote:
Ultimately, I think that to guard against self-delusion in your aikido life (which might or might not include kotodama training), you need a teacher, whom you can trust to tell you where you have erred.
Well yes but we do not always have the good fortune to run into Mr. Myagi. Though one might say "when the student is ready, the teacher will come. And though that may have sounded sarcastic, I really have experienced that to be the case.
I think you took this more personally than I intended. In most traditions, if one pursues spiritual training of any kind, one needs a spiritual master, a Sensei in the true meaning of the term, who is in a position to guide and point out potential and actual arrors. In other words, it is very difficult to be an accurate judge of one's own progress. In a budo like sumo, there is always the tournament, which provides an objective measurement of at least physical skill. Though even here, the spiritual aspects of sumo tend to be handled by someone like an oyakata, again, a 'sensei'.
Obviously teachers may appear, or they may not. But my point was that people doing aikido training, and also whatever exercises go with kotodama training however this is conceived, still need teachers, or senseis, of some kind.