Hi Gail,
I think that I might be growing it. I got a couple of small pieces of rhizome from a contact who collected it somewhere in Tibet. He thought it was Caltha sinogracilis rubriflora but it appears to be a dwarf, high-altitude Caltha palustris purpurea.
I haven’t found it to be too easy. I managed to get two plants from the rootstock I received -both flowered then one promptly died whilst the other just clings on. I cross-pollinated and got some seed which has germinated well. The potful of seedlings are now in their 2nd year but are hopelessly entangled. So far I have tortured this plant in pots. Perhaps it might do better in a cool, moist spot in the garden though apparently it is a high alpine species growing along streams in moist mossy banks and in damp alpine turf at between 4,000-5,000m. I’m not sure if I can get more seed this year but hopefully I can grow on the seedlings to flowering size for future seed. If so you are welcome to some -it germinates well when fresh.
Below are some images of my adult plant (which did not appreciate the Easter heatwave and is currently not looking great though the seedlings are fine):
