My comfrey bed gets a lot of shade.
My house shades them in the morning till about 11 a.m. They get an hour or two of direct sun then the sun goes behind an oak and there is filtered sun till 3 or 4 p.m., then an hour of direct sun, then more filtered shade. There is some direct sun very late in the p.m. Thus is all in late spring through late summer.
Now that the sun is lower in the sky, the poor plants get more filtered shade than sun. When the trees
lose their leaves there'll be more sun but by then the comfrey will be dormant.
I live in northern California. The comfrey do well here with mild winters and hot, very dry summers. Possibly the shade is an advantage to them.
After typing all that, I just remembered the two plants I have on the north side of my house. They get no direct sun except for a couple hours in very late spring through early summer, when the sun is highest in the sky. I think
your plants will do OK.