Looks like it's pruned back again...not sure why cutting back at knee height? Scaffolding at knee height? Will you be laying on the ground to pick fruit lol. I don't see anything to heal over...angle seems fine, the more you cut the longer it take for root developments and growing up.

I read a book called Grow A Little Fruit Tree that recommends this method of keeping trees small, but they come from CA. How high do you put a scaffold?

Thats a matter of preference...I like mine high so easy to work under the tree like cutting grass etc.

I wonder if the upright tendency of this tree will ultimately produce a new central leader. If so, I may go ahead and let it, and ultimately prune off these lower limbs as per your advice.

Pretty sure it will...sometimes you might encounter some freeze back.. but shouldn't in your zone.

Leslie, I tie young branches down to the angel I want to a stake in the ground. After they harden, I remove the string and stake. The cut will heal.

It did not grow back a central leader - it now has a terrific vase shape.