I moved PR 2307 to a new issue, #30728 Modernize configdialog. My comment that internal Var names "can lowercased (PEP8) and otherwised changed" was anticipating such an issue.  The point for this issue was to contrast Var names with the cross-version config names that we must not change.

I don't expect anyone else to fully understand this without a couple of hours of code study.

Once #22115 was merged, I could have gone ahead.  Since I did not, I should now wait for at least part of PR 2307 and #30728 since the patch for this would break parts of the existing new patch.  I could work on a new test though.