As I mentioned latency is indeed an issue, but I don't think it matter that much. Your pixel will be offset by the movement during this 50ms (probably more) which will be a typically a few centimeters, so edges will get a little blurry but I'm not a light painter expert.

If it is really a problem, assume pose velocity from the previous frame positions and correct for latency and turn off the screen if acceleration sensor is greater than a value.

That's true, if you have a phone you can use the sensors on it to do dead reckoning in the interim. I'm not a mocap expert, but this seems very doable! It would be a great idea.