[Wim Lewis]

A couple of off-the-cuff ideas, from someone who's not familiar with ScriptingBridge:

Have you looked at the Python "appscript" module? It might be easier to use because there's only one layer of translation going on (Python to the AppleEvents object model)*rather than two (Python to Objective-C to AppleEvents).

My other thought is that you might have to insert the newly created object into a container before it becomes real. Applescript-accessible objects can't exist in a vacuum; they need to be "in" something (possibly just in the application object). ScriptingBridge might be waiting for you to provide the newly created task with a location before it actually sends the AppleEvent to create it.