"I also recall the initial report said nothing was recorded on the right side of the cockpit.... "
If it said that, it's just plain wrong. There is a ****load of sensors related to the right side (only some of them frozen or impacted by the freezing), and all parameters related to anything other that what had frozen was still valid..
A 400ft low could appear on the right PFD. Then, the DFDR records from the DMC.
This low could appear due to a change in available data for computing altitude.
More precisely, TAS and Mach allow you to correct for position error. Without them, position error correction is lost.
I don't think this bus would be touchy about overspeed. It has a high speed protection law in normal law that would save the aircraft in close to 100% of situations with normal law.
However, I have no idea what the THS did during the incident.
The THS position is a truly important flight parameter and I do believe airbus should display it more clearly.