I think that you will find it very rare for a specific containment test to be carried out on anything other than the highest energy blade which is the fan blade.
Typically all other blade stages are validated by experience. Also only the fan stages have used anything other than metal casings in the big iron and for the newer fan, typically Kevlar not carbon fiber.
The engine can not rely for containment from the cowl since that is a piece specfic to the arcraft installation.
The report above of completely missing baldes from several disks might imply a significant stretching of the disks to release them from their slot grooves if indeed the complete blade is missing from an open slot.
At any rate I would rather see blades liberated compared to disks so mitigation worked!
One might consider this a good validation if it turns out to be only a one-off event.