Here is all I know about Hoya Mistie from the woman who sent me the plant:

Hello Doug.. I received a cutting from AH Hoya that appears to be a new Hoya… Hoya Mistie. I searched the Hoya pages I’m on and can’t see that anyone has yet sold it.
I did some research and contacted the “breeder” in Poland and found out it’s a seedling from erythrina (mother plant). X father unknown. Here’s the info I have from the grower.. his description and picture of the flower.
I have several cuttings rooting and would like to send you one if you are interested. I’d love to follow your journey with this Hoya.

Take care, Mary Hammond