Complex sentence: The lens is "not" compatible with Sony's 1.4x and 2.0x teleconvertors as it is physically impossible to properly mount them to the lens mount without damaging the rear lens element.
Split into simpler sentences: The lens is "not" compatible with Sony's 1.4x and 2.0x teleconvertors. It is physically impossible to properly mount them to the lens mount without damaging the rear lens element.