Mislabeled plants are quite common and some people are very sloppy with names. I agree with you that this is very likely not a Jovibarba heuffelii.
Hybrids are definitely possible and I have seen listings of hybrids between heuffelii and other species of Jovibarba. However, if this is an interspecies hybrid, I think a better, more accurate label would have been appropriate.
I think your best bet is to contact the seller of this plant for further information. They may be able to help.
