A problem with the tracking status is that by default the page is completed On: Show, i.e. maybe before the play action is run. In my test it didn’t work consistently. Using a separate variable should allow to specify exactly how long the audio must have been played before it’s not played again.
It would still be better to default the tracking status of a page to “in Progress” on show (if it’s not completed before) and to “Completed” on hide.