In attached blend file I do simple macro (simple_operator):

• subdivide mesh (in edit mode)
• perform cut with knife tool, by user
• deselect all.

- blend file with macro
Now, I know knife tool dosen't support undo, so it is greyed out in F6 panel, after executing this script and calling operator. But undo stack order is reversed from what I see.

What I mean is, operations performed by macro, after knife_tool, should have available undo properties, but they are disabled. What blender does is, it enables F6 properties, for operations performed before knife. This makes no sense, because as soon as you change property of operator performed before knife, knife operation gets cancelled, and everything after that gets canceled too. So you loose all operations performed after knife operation.
How undo stack should work for macro is:

• all F6 properties for operations performed before knife should be disabled (unsupported)
• properties for operations performed after knife should be available - this way they could be re-executed after property change in f6 panel.