I don't think it's a good idea to resurrect 2-year old threads, especially in addition to the other thread you've already created. As moderators have previously suggested, it's better to link to the old thread instead of bumping the old one. I'll answer the questions here though for posterity, but wouldn't mind if moderators lock this thread to redirect the discussion to the new one.
Yes, CoreFoundation is a private API on non-Darwin platforms, it may go away or change without notice in future versions of Swift.
No, as it's a private API that should not be accessed anywhere outside of swift-corelibs-foundation.