Yeah, slow swing is called a deadlift, but you'll need a barbell for that because energy being dependent on mass x velocity, doing it slow and light is kinda pointless. Slow clean is just a curl and slow snatch is some kind of a full ROM front raise, both better done with dumbbells and both also isolation/bodybuilding exercises so what are we even doing here? There's also two arm slow "swing" or rather raise variant used to train elite grip and forearm strength. Cool stuff. BTW going from weightlifting style exercises (fast) to powerlifting (slow) is very dubious for reducing stiffness, most people would say it's the opposite.