Hi Michael,
Thanks for pointing that out. The Help > Keyboard Shortcuts hasn't been updated to show the reassignment of that shortcut.
I couldn't find a built-in shortcut for align left and right. You'll note that in the menu when you go to Format > Text you will see no shortcut for, say, Align Right.
But you can easily assign your own keyboard shortcut in System > Preferences > Keyboard > Shortcuts > App Shortcuts:

To add Align Left, click the +, choose Numbers in the Application dropdown, and fill in your desired shortcut:

You may have to experiment to find shortcuts that will work on your machine (i.e. won't conflict with existing shortcuts). On my machine control-command-[ and control-command-] work for alignment.
After you've assigned the shortcuts you'll see them in the menu.

SG