I’m running OS X localized in French and recently started using custom keyboard shortcuts extensively. But I’ve come across a few menu items for which I could not create a shortcut. I realized that all these items contained apostrophes. Not the same apostrophe as the one on the keyboard though (‘ vs. ‘ which is a single quote, ascii 39).

I managed to find the right char in a *.strings file inside the Ressource/French.lproj folder of the application package (Teminal.app in this case), which I could then copy and paste in System Preferences