What version of Flash does TBS 4 export to? Does this support all the new features like feathering and dynamic shadows?
According to the User Guide, TBS 4.0 exports SWF in version 6, only. So, it is well behind current Flash capabilities.
An option to your workflow, is to get the Toon Boom Studio Importer plugin for Adode Flash application, import your TBS project into a Flash document, do more stuff in Flash, then export your SWF, setting to whatever SWF version is desired or applicable to the features you need.