I doubt that it’s micropropagation, if it has anything to do with the Corals ! They corals are the very easiest peonies to propagate quickly, because of their adventitious nature, and would be the last peonies that one would want to use micropropagation on !
Having said that, while intersectionals have been successfully micropropigated (although there have been some problems with them as I understand) using tissue culture with herbaceous hybrids *has* been done too. I know of a situation where people grew thousands of several expensive varieties from tissue culture many years ago now. Apparently it’s expensive, because each individual variety needs their own special growth medium, and the expense of figuring that out for each one is significant. Once these plantlets were grown on, and then planted out in the field, apparently the plants were “lazy” and wanted to remain “youthful” for much longer than small plants grown from small divisions would normally take. So while tissue culture with intersectionals may be profitable, apparently tissue culture with herbaceous hybrids has not worked out to be a profitable thing. At least not so far, as I understand.