Apart from the manifest.xml in exportedfiles.cab, Event Viewer and the ULS logs, is there any way to identify which object is causing the problem in content deployment?
You could try telling SharePoint to keep the temporary files. This can be done using stsadm:
STSADM -o editcontentdeploymentpath -pathname -keeptemporaryfiles Never|Always|Failure
You can then look inside the various cab files and figure out what is going on (I didn't say it would be easy). This blog article has some suggestions.
Stefan Gossner has a good blog article on common content deployment problems.