Higher frequency sound tends to be directional.  This means that speakers tend to sound best when the high frequency drivers are pointed at your head (where your ears live).  In this case, the higher frequencies will be directed toward the ceiling rather than your head.  It would probably sound best in that position if it were pointed down toward your sitting area (maybe put the rear leg on a book (or two) if this doesn't make it too unsteady or look too weird). You should definitely run the room calibration given it's in the corner and close to the ceiling, but that will not help the higher frequencies going toward the ceiling rather than the sitting area.

Just buy the wall mount and hang it on one of the walls, it will look better, sound better and save some space !