Are you asking if Spring Social supports handling the callback from Facebook's registration plugin (including custom fields)? If that's your question, then the answer is no.
Awhile back I created https://jira.springsource.org/browse/SOCIALFB-7 to track this as a new feature. But it never bubbled up high enough in priority for me to implement it. But I can see how it'd be a very useful feature to have when working with Facebook. If this is something you want, please vote on the issue. Or better yet, if you're so inclined, try to implement it yourself and submit it as a pull request...I'll be happy to review it and maybe merge it.
Spring Social Project Lead