The scripts need to be rewritten. The error indicates a problem with he syntax of the script.
You can edit the scripts to disable the unsupported events.
Use the Open Scripts Folder command in the Applescript Handler popup menu.
Find the Speak Events script and double-click.
Find the lines that start with,
on received local...
on received remote...
put two dashes in front of each line so that they look like:
--on received local screen sharing invitation from theBuddy for theChat with eventDescription
--say eventDescription
--end received local screen sharing invitation
and
--on received remote screen sharing invitation with eventDescription
--say eventDescription
--end received remote screen sharing invitation
Save the script and it should work properly, but won't say anything for screen sharing invitations.