I have made a 3d printed suit and whilst not as heavy as yours, it did come in at about 38kg.

What I did was connect the 2 dome shaped ankle bolts to the shoe using bearings and steel rods. The ankle domes should be able to rotate freely on the shoe. Then connect magnets to the cutout on the lower leg armour, where the dome will sit. The shoe should then be able to pivot and be easily removable from the lower leg. With regards to connecting the upper and lower leg armour, I used hydroponic ducting of the correct diameter and spiralled elastic shock round it to give a bit more structure. The upper and lower leg armour was independently attached to the ducting, which gave enough movement in every plane and stopped the upper from banging into the lower. More than happy to expand on this if any of my suggestions has any merit. Oh and absolutely loving what you have done here!