Some years back, Tsunako Miyake did an invitational seminar on Koshiki no Kata in Texas. The folks that were invited were yondan and above, so I didn't get to go since I was Sandan at the time. But LF Wilkinson, the Thoughtful Sensei of the Aikibudokan did get to attend Miyake's seminar and he had some great comments on my previous post.
Regarding the specificity of corrections and the precision of technical specifications for Koshiki no Kata, he writes...
... When [Tsunako Miyake] taught this to us years ago she was very specific in some of her corrections, less so in others. I think that the corrections were for those areas in each of us that had too much slack (while each person's "other" areas were already tight enough and needed little to no correction). For my uke and I her specifics were ...
**to him - more body/less arm ... meaning he was thinking with his arms and not his center and she continually corrected the placement of his body relative to mine (hip to hip, chest to shoulder, etc.) and where his feet went. Since his center was in the wrong position relative to uke, he was resorting to his arms to catch the slack and force the waza. So foot position is important and cannot be sloppy.
**to me - the only correction I received was "squat, more lower" and upon my stating that "Sensei, I do not understand" ... she commented that I walked too upright/high and too smooth "like Aikido player ... must walk like Judo-man" and those comments didn't stop until I was walking not in a squat but in a lumbering, low-center saunter of sorts with my head straight up (Aikido-man rooted to earth, as-it-were).
Once I got it right she said, "ah good, now you look like an uchimata man" which blew me away because my first judo teacher said exactly the same thing and had me specialize in it (so what came 1st ... the walk or the throw?? I dunno, probably my walk since I was tagged with that when I was only a green belt).
So in my case, everything was pretty much in line with what was needed except my center initially was too high and that she wanted me to lower my center (even on the approach before tori & uke ever engaged) in order to get UNDER uke's center for each throw.
Unlike Judo .... this kata requires (with a few exceptions) tori's center to be lower then uke's as both are wearing armor and uke cannot have his center lifted to "roll" over tori's center (and tori cannot effectively use his arms). Without trying to recount all three days and the corrections she made to the group and to the judo people (who had their own set of issues) she was VERY specific about certain areas such as where the foot went and where tori stood and placed himself relative to uke.
Other items such as precisely where tori placed his hand (on uke's shoulder for example) on some of the sacrifices was less precise leading Lynn and I to the conclusion that in a kata of this level some items must be critically precise in order to express the underlying principle for each waza while other items are less critical .... likely because the "more" critical items assist the pure form of the principle while the "less" critical items have much less effect on the pure form of the principle and therefore have less of a change of "queering" the pure form if a hand or foot is slightly off on inch one way or the other.
I would offer that Koshiki MUST be VERY precise .... just not in the way we would see with a 1st tier Yudansha kata (1st tier being Shodan thru Yondan). I think that precision is precision ... it's just that the precision required for a Shodan is not the same as needed for a kata of this level and the ability to tell what parts must be exact and what parts can have a little slack here and there is what sets the shodan apart from the hachidan.
I highlighted that last part myself - pretty outstanding I think.