Keith, have you tried any of the frost hardy species already in the more commonly available colors? If you have, please just ignore the rest of this, but otherwise I'd like to offer a few ideas to get
Cyclamen hederifolium better established (I don't grow any other) :
If you plant
Cyclamen hederifolium from dry tubers the best time to do so are in summer or early autumn when they are dormant. They do start to grow
very early. Also I think it's best to ignore any advice about planting deeply to improve hardiness of
Cyclamen hederifolium. My result from deep planting in ordinary garden soil was disappointing, with poor flowering and vigour and eventually the death of the plants. Since then I learned to plant these rather shallow under a deciduous tree and the difference in flowering and growth is already in its second year rather striking. The fallen leaves, if not too deeply forms a nice natural mulch, far superior to deep planting. I have mine under a European Beech tree. Apparently they can easily rot if they don't get dryish conditions during summer and from what I read this is the most usual reason for failure with them, not the cold. The tree will help with this, sucking excessive moisture out of the soil.
I hope you will find the colors you are looking for as I know that they can be a bit hard to find, especially the darker pink ones. I have some plans to get these myself, even if I perhaps will need to import them (the selection here in Sweden isn't great). I think they would be really lovely in a mix
Edit - Spelling