I got this traceback while I add the Text/Layout plugin in my page.
I think it must have something to do with this line and model heritance:
That it, for semanticeditor plugin.model is cms.plugins.text.models.Text so the name
of the plugin is wrong. Not sure if it's a django-cms or a semanticeditor bug though
neither how to fix it.
It looks like you haven't done a required syncdb or migrate command.