Hi Dancing,
Well on Okinawa everything was Okinawan karate and in the prior days there was no record of how anything did anything. There are multiple variations of the kata, such as the published 15 versions of Patsai, and somebody had to changes things. In doing so they didn't lose Okinawan karate (for everything was Okinawan karate) and in earlier days many didn't become instructors until after their instructor's death. Watch the variations between Kyan's students.
It's not impossible the true tradition was everything changes, and change in all Okinawan karate is the only constant?
I don't know. In my case my instructors trained on Okinawa in 60 and 72 and from their studies, direct observations of what was being taught and tracking returning students what they did, ended up with many variations on the kata. I was taught a bit of them.
In turn I could teach many different variations but choose not to. But after 37 years sometimes I begin a kata with one variation and inadvertently end with another, both pure style from what I was taught. I don't teach that way but it still happens.
And there are no rules, though it sometimes would be nice if there were. I really don't pay attention to what others in my 'style' do, I only track from my instructors, but not having been taught there was a right way, instead that you must work to take the way you do it right, I'm less concerned with change occurring. I've had to deal with that from my first day.
Then again I don't bunkai either. I was never taught any 'bunkai' and in turn I can take a movement and work it successfully with dozen's of applications from my own efforts. Bunkai seems to restrictive. If that's the way you were taught, cool, I've just had to follow a different path.
Seems to me if there was a right way, and the instructor didn't document it for everyone's reference, then they created the actual situation, not the instructor following them.
When you train the same people for 20 or 30 years you'll find they get many different paths from you, one as right and pure as the next.
pleasantly,