Evelyn, I find comfrey to be a pretty forgiving plant. I have it in full sun (Pacific NW, so not intense sun) in my herb garden, but it has also hitchhiked to a couple shadier spots where it is doing well (I must have dug up bits of the root when moving plants close to it). It also popped out of my compost pile, where it is dumped on regularly but nevertheless thrives. I like it there as a bit of a screen. I'd let it stay in your shade garden and see how it does this coming season. If it is obviously reaching for more light, just move it again. It transplants well.
