From the Qubes documentation “Passthrough reading and recording (a.k.a., “burning”) are not supported by Qubes OS. This is not a limitation of Xen, which provides scsiback and scsifront drivers, but of Qubes OS. It will be fixed in the future”
I would suspect a low priority, but is there a status update?
I think USB CD drive recording should work well, should not they?
At least reading from USB CD-ROM drive works perfectly well for me, I think burning will also work.