The Immortals will not allow the sphere to be used frequently enough to cause this. If used to travel to Matera, the first immediate problem the user must deal with is the lack of air to breathe. If they are prepared, they can survive their initial trip, but Matera is also home to the city of Immortals, who will kindly but firmly relocate any errant mortals back to their own homelands. Travelling to Patera is extremely risky. Because of the crust composition that renders it's surface area invisible, even the sphere cannot accurately show the precise locations.
Players stand a good chance of being teleported into a mountain or worse.
The sphere is one of the most powerful artifacts ever made, it is doubtful it could ever be destroyed on the Prime plane of Mystara. Throwing the sphere into the heart of the Hollow World sun. Shatter the sphere against the Nucleus of the Spheres.