you're right that they can regenerate back human body parts.
but, when I say regenerate, I'm refering to actual regeneration (Claymore body parts, NOT human body parts as they don't count, lol).
very few offensive type Claymores can regenerate (actually as well there's very few defensive type Claymores that can regenerate too) as regeneration is an advanced ability usually only available near 80% yoki release, which is dangerous due to possibly Awakening.