I am not the creator but I am a robotics engineer. The robot in your link is an industrial robot with a lot of strength behind it. The robot in this project is

I am not the creator but I am a robotics engineer. The robot in your link is an industrial robot with a lot of strength behind it. The robot in this project is comparatively lightweight, with thin 3D printed construction and very small motors with little to no gear reduction on the drive joints. Based on how this robot is constructed I would say it is incapable of breaking any bones on a human. In the business we call this "inherently safe", meaning it can't meaningfully hurt a person even if it malfunctions. Put simply, the robot that hurt the child was a very strong industrial robot, this robot in contrast looks just strong enough to move chess pieces and not strong enough to hurt a person.