It looks like the behavior with Document 1 only happens when the Word document width is either the width of the screen or close to the width of the screen. That's why the 2nd run (Document 2) works, because the document width is no longer close to the screen width.
Guess this is what @ccstone meant?
The system accessibility blocks changes that will put any part of the window off the screen. Keyboard Maestro makes efforts to work around this by moving and resizing twice, but maybe the move is being deferred.
That was what I said. A second run accomplishes the task.
BetterTouchTool probably does what you said. When the resizing is slow, it appears to have been resize twice. So it must be somehow the 2nd time of KM was blocked, but the 2nd time of BTT runs as designed.