I thought they were talking about a visual bug where cavalry shields clip through the steed and not the actual shieldwall formation, which is kinda weird and pointless in Medieval 2 (it's only ever caused me to take more casualties tbh).
yes, they were talking about the visual bug with the shield on cavalry units. They didn't said they would give shieldwall to the Romans...
We have no plans to give the Romans or anyone else the shieldwall ability.