We are missing the AOA parameter graph, in order to know if there was a stall, a spin or a spiral dive. It looks they never recover fist time though
Yes, it would have been nice to have the AOA.
The secondary stall seems to have happened between 01:46:12 and 01:46:15.
Look at the roll angle leading up to time 01:46:15, look at the g trace which peaks about that time, look at the change in the slope of the pitch angle trace at that time leading to a pitch down, look at the elevator trace which peaks at 01:46:12 just before the secondary stall. Look at the effect on the airspeed which has a peak at that time and then starts back down.
Looks to me that they hurried the pull out from the dive and overdid it.