Thank you for the PR.

I think this is a difference in expression between Japanese and English, or my Japanese ability.
Could you understand the following explanation?

local: has a closed scope within a buffer, variables in one buffer are not shared with variables in other buffers.
global: has a global scope like defvar.

Ok, then editor-variables can be both local and global? If so: the global is the default for the local, correct?

How does the changed-value-hook play into it? It it only called when the global is changed or whenever the value is changed?

change-value-hook is called only when the global variable is changed.
Currently, it is not used in any other scope.

I changed the doc-string of the editor-variable class to be clearer.

One Implementation question:
The kind parameter passed to variable-value is the scope of the variable correct?
Why is the default value for kind different between variable-value and setf variable-value (it's :default for the getter and :global for setf)? Especially since there doesn't appear to be a method speciallizing on the :default kind.

The kind parameter passed to variable-value is the scope of the variable correct?

yes

Why is the default value for kind different between variable-value and setf variable-value (it's :default for the getter and :global for setf)?

Isn't it the same?

Also, Thank you for the changes.

Ah sorry I meant the variable-value-aux and setf variable-value-aux methods.
here:

Also would it be ok if I rename kind to scope?

Hmm, I don't know, but there doesn't seem to be any particular reason.

Also would it be ok if I rename kind to scope?

Ok, I'd prefer it that way too.

Ah sorry i figured it out (a simple M-. answered my question 🤦‍♂️).

You can merge this, unless you have any additions/changes.

It's very good!
Thank you very much.