Great! It all works now.
I generated the NECx2 codes and then used the IRPanels app to test the 256 codes. Apart from the Ext.2 that I was missing, I found a few other surprises :
* AV input (didn't know it existed)
* discrete Picture Modes
* discrete Picture Sizes (except for Auto-Wide, which is weird)
Also weird is that there are no discrete Sound Modes (not that I regret it since I use a separate amp anyway).
I've submitted the mappings file.