I do know that the epub specs allow reading systems to ignore any and all metadata links (even ones internal to the epub). With that kind of "permission," it's not likely that any commercial epub rendering engines will be very quick to utilize them.
Just mentioning it; not making a judgement.
Also keep in mind that Sigil's EPUB3 support has not been extended to 3.01 or 3.1 (let alone 3.2). The spec is too volatile to even attempt to keep up.