I have been following this thread with interest. I have had a fair amount of experience with wave and rotor, both as a passenger flying up and down the Rocky Mountains and as a tow pilot up to 10,000' and in gliders up to FL240.
I have always found (and read) that the worst turbulence is associated with the rotors which usually occur at or below the tops of the mountains and that above the mountain tops, the flow is laminar and often uncannily smooth.
Was the high altitude turbulence encountered over the Pyrenees due to wind shear or high speed penetration of short period waves? I imagine waves that appear smooth to me at 50 kts, might seem quite different at 500 kts.
Classic "rotor" seems unlikely at the altitudes reported. Are there any meteorologists who can comment?