Hi Bec,
Actually, the problem is not linked to non-roman characters. The Search function in glossary does return any results for an entry consisting of only one character, whatever that character is.
Experiment: new entry "a", definition "first letter of the alphabet". Search glossary for "a", search return: empty!
I expect this is by design, but it also looks like a bug. I will enquire some more and open an issue in the bug tracker.
Joseph