Any way to re-enable the right Alt key?
It's possible to tweak your keyboard operation in specific and low-level ways, but I've only just begun to look at how that's done properly (i.e. without causing my X server to have fits).
For example, I found that the Firefox shortcuts did work with my lefthand ALT key (LALT), but did not
with my righthand ALT key (RALT), so I had the opposite of your situation. This had no practical impact on my use of the keyboard (as I don't normally use RALT), but I went snooping into the keyboard configuration section of my /etc/X11/xorg.conf
file and found the following...
Option "XkbOptions" "lv3:ralt_switch"
That code meddles with my RALT key in a way that's meaningless to me, so I disabled that option (I put a #
at the start of the line), and now my RALT key works as expected. A fix for your glitch might be as simple.
I've taken a quick peek at various config files in GNOME Bianca, and I see keyboard definitions that are specific to Sony and others, but I don't yet know how those might be applied.
Just a matter of time til this Linux n00b susses it out, though.