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