Perhaps it does provide a way of displaying the keyboard layout for every font but I have not discovered it.
It's important to understand that OS X and Word (starting with Word
2004) are now designed to operate in Unicode. Instead of switching
fonts that replace Latin with other characters, you can usually forget
the font and switch keyboard layouts in system prefs/international/
input menu. There is no keyboard layout for symbols and other
characters that do not relate to languages. For those you use the
Character Palette. To see which key does what in a keyboard layout,
you use Keyboard Viewer, which is also activated in system prefs/
international/input menu.
You may still be able to use apps in non-Unicode mode sometimes with
old non-Unicode symbol and other fonts, but Keyboard Viewer often will
not recognize these fonts.
Chinese and cuneiform have many more characters than could ever be
reached directly via the keyboard, and thus to input them one uses an
input method where multiple characters are typed to produce a single
ideogram. For the purpose of just displaying a few characters, the
Character Palette is the best approach.