Hi Dave,
Here is a solution for your problem (using Moodle 1.8).
1. In ► Administration ► Appearance ► HTML Editor
Font family editor fontfamily: at the end of the list of fonts, add ,Lucida Sans Unicode
at the end of Font list editor fontlist, add:
Lucida Sans Unicode | Lucida Sans Unicode
2. At the end of one of your current theme's CSS stylesheets, add this declaration:
.que .answer input {font-family: "Lucida Sans Unicode";}
In teacher questions edit mode, short answer question type, type the answers to your questions using your usual (keyman) editor for Unicode characters.
In student mode, answers will be correctly displayed, see attached screen shot.
Hope that helps.
Joseph