I don't know for sure but I would guess that since it re-writes the URLs to be SEO that it would have some issues with CB Connector as the CBC builds its own links internally.
Easiest implementation would be to make a phpbb-seo plugin for the CB Connector then it should work.
Unfortunately I don't have time to make a phpbb-seo plugin but it should be fairly doable by starting with the plugin for phpbb2 I assume it is built off of phpbb2 versus phpbb3, but don't know for sure... if built off of 3 then just start with phpbb3 plugin...