The torpedoes are referring to how their propellor’s edge cuts through the water.
I’m guessing the bullets supercavitate because their shape allows them to apply higher pressure on a smaller point of attack which then boils off the water in front of them allowing for reduced drag.
The torpedo bodies themselves supercavitate, not just the props. They couldn’t be referring to the props because the supercavitating torpedoes don’t actually have any as they are rocket powered. The VA-111 Shkval torpedo is available on the world arms market, has been available for decades and has a demonstrable top speed in excess of 200 knots for the export models.
Wrong, from what I read, the Russian torp is rocket powered and bleeds off some exhaust to form the bubble shroud.
No propeller.
Not, or barely maneuverable.