Upvote:1
The only problem you can have if you will stay more than 28 days inside the Schengen Area.
You can back to Tunisia from France or another Schengen country with the same or a different airline, but because your visa was issued by Austria, it's better that Austria is part of your trip.
In addition take with you a printed copy of your return ticket details and hotel reservations.
Have a nice stay in Europe!