I'm not surprised the glossary operator doesn't work in eZP 4.0 simply because it hasn't been ported yet :-)
We are in the process of porting a site to eZP 4.0 which basically means porting extensions. That site includes the glossary operator so we will have to tackle it in the very short term (read: next week).
Besides needing a port to eZP 4.0, the extension basically needs a rewrite to update the code. The foundations of the extension were created in 2003 I believe.
