Hello Mark:
I find foot problems often can be reduced by looking at the joint directly above it (knee). Same for other body parts too I guess...
As long as you have contact with the ground, I doubt it will be as serious a problem as our "dissection" of them might seem??? Regardless, its something you'll be playing with for a bunch of years... until you are content with the results
I vaguely remember a book in my library which spoke to the ankle, foot issue, let me see if I can recall which one. Might have been Karate-Do Foundations (Fueller?), might have been Brian Frost's book. Have to ponder that a bit.
I'm a "Shorin" stylist both by lineage and preference. The knee bending is a basic-fundamental of the particular art I practice. Don't forget to press your knee slightly OUTWARD, once you have the knee bending issue down a little more.
Its maddening all the tiny little parts you can focus on, if you turn your attention to that particular "X" level. I know exactly why all the fabled masters went off into the mountains to spend some time. They literally went INSANE trying to figure this all out

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Thanks for sharing your different kata with us, we mean no offense/harm by our addled thoughts, comments...
Jeff