Halion sonic se content is editable in halion 6. But most of the stuff that comes with cubase has copyprotection and is locked away. Someone once said it is due to license restrictions or something like that. Check out an answer I gave to a similar post how to find out:
Also if you create your own halion sonic se content with the library creator, you can decide what to lock and what to keep accessible.
I hope that sheds some light 