check this website out- it tells you which will propagate true and which will not.

https://mrec.ifas.ufl.edu/Foliage/folnotes/sansevie.htm

Great resource, it seems to not have a definite answer to how Golden Hahnii's will propogate, and I think I've actually heard they'll revert to regular, so I thought it was interesting that my leaf produced another golden, (or possibily a solid gold)

" One of the leaves had a root on it (you'll know what I'm talking about if you've seen it) Like a dark orange stub of a root. " - this is what you wrote. In this case, this is not propagation from leaf, but from a crown division (ok, a very very tiny bit of a crown); in such case, the pup takes after its mother, i.e. it is variegated. Pretty success though and a very nicely coloured plant you have..

No, still a leaf propagation. It sprouted from the all yellow (white) section of the leaf as you suspected. . Keep attached as long as you can and enjoy it while you can. In almost all cases it will die. I had a few from time to time. I did hear of one continue to live after it developed a very small amount of green. I posted pictures of mine in some past post.