Lack of shortcuts in context menus don't bother me, I normally navigate context menus with the arrow keys - because calibres book list context menu is configurable (hooray) I can put the things I use a lot at the bottom - yes at the bottom and hit up arrow.
It was having to grab the mouse to press the button when I noticed no accelerator, but its not something I do often. I should unpack the code and do it myself.
Added : Tested on 1.43 64bit install version with my real libraries - no problems works fine
BR