You get sharp corners from torque (which begets acceleration). You have servos and high ratio gear reduction so you should be able to crank your torque up in motor tuning. If you still continue to have bad corners then you may have some backlash in the system. Whatever your backlash is in the gear box is multiplied by the pinion gear setup ratio.
If you are cutting thin material use the smallest tip and current setting combo (by the charts) that you can so you can cut at slower speeds. It's easier (quicker) to accelerate from 0 to 120 IPM versus 0 to 333 IPM.
Your acceleraion and deceleration in motor tuning determines a lot as to how far away from the actual toolpath your cutter will deviate. The software tries not the make moves that violate the settings and could cause a servo fault.
The amount of mass you have to move with a given torque predicts the acceleration curves. If you have a big heavy gantry then you need lots of torque to make it stop instantly and accelerate in another direction.
I don't know what size gantry (weight you have to move) or the servo motor torque ratings or if it's dual drive (two motors). All those things effect the perfomance of your table and predict the acceleration you can acheive and ultimately the tightness of your turns.