Chris - I realize they are rough and ready translations but thanks for doing them.
Please note that these are my interpretations of the terms and each of them probably need a longer description than I have written (and I have consciously steered clear of some of the IS interpretations such as using dantian,etc. )
Actually putting them in sequence there is a nice harmony to them in that in some ways the first is the basis for the second pair and the third is the basis for the fourth pair
Stillness and Movement - movement trains techniques and applications (speed, angle etc.) stillness trains the whole body integration (mind, body, fascia)
Leading and Loosening - I would pair up the leading as the energy of taking your opponent off balance, and loosening as the ability to remove tension from your body to slip out of locks and reverse techniques
Relaxation and Congealing - ability to have a relaxed body without extraneous tension and congealing is the ability to link up the body into one unit to fajin or issue force
Opening and Closing - storing and releasing the energy (related to usage of the back bow) - I know the character is for separating but I think the concept is the same as opening.
Just talking about In/yo seems too abstract for me... as In/yo is a relative concept and means different things in different situations.
I disagree with your descriptions of Ueshiba's list
Chris wrote: Ueshiba described the "Hachiriki" as an active force, a quiet force, a pulling force, a loosening force, a splitting force, a combining force, a melting force and a congealing force (you can see that each "in" force has a matching "yo" force).
Your redefining without enough information. They clearly do not
line up with say; the eight jins of taiji, though we can make similarities. Ueshiba has many other newly translated passages that do discuss connecting and the use of jins, but are not nearly as complete (so far) as similar Chinese writings. I do not think that these passages are exactly what people are looking to have them mean in regards to say a taiji perspective on eight jins. I could argue both sides against the middle and presume quite a bit. I'd rather wait until more of his previous supposedly unintelligble meanderings and writtings that skipped over and mistranslated are translated correctly-hopefully not by the type of sources who screwed them up in the first place- so the clarity of his research and his methods are made known.