Until the day of this post writing, the front and rear upper linkages of the leg were connected to the motors using aluminium flanges. Generally speaking, this component is great but performs poorly if an overhung stress is applied to the motor shaft, causing vibrations that tend to increase after intense testing of the leg. To (hopefully) fix the problem, I changed the design, substituting the flange with an aluminium bracket that can be secured to the motor shaft using small set screws. Additionally, this design increases the contact area between metal and plastic, improving the force distribution.
This configuration has been tested by running the same tests performed with the previous design. Results show that not only the vibrations are reduced (as well as the chance that screws get unscrewed due to vibrations), but also improve the stability of the leg when it was tested sideways and upside down.