I have no experience with the two variegated plants you mention, but Eleutheroccocus (formerly Acanthopanax) siboldianus variegatus is a very handsome variegated shrub for shade.

Yes. I have a variegated red-twig on the north side of my house, in a corner next to my porch. It does really well but doesn't bloom much. They do get pretty big though.....

Acuba japonica does well in shade. It can get a bit large, but it is a slow grower. I have it planted in the shade at the back of my property, and I can see it from the house. It is also evergreen in zone 7. Mine is green with yellow spots/blotches, but I think there is one with almost white spots. Verigated hosta work, also; you could try a very large one.

Though it's not a bush, but fallopia japonica variegata could attain 4x4' proportions and it's extremely brightly variegated plant for full or part shade.
Variegated hydrangeas will be either not bright enough or will bloom poorly in a shade. Even worse, they are early bloomers and most often than not swelling buds will be killed by late freezes that you may experience in z6.
Variegated dogwood (Elegantissima or dwarf 'Ivory Halo') will do good in a shade, though both of them succeptible to leaf spot and may not serve your purpose if location doesn't have a good air circulation.

Forgot to mention, I'm too, endorsing Eleutheroccocus as a great shrub for any tough situation, be it wet or dry shade.

At my previous property I grew hydrangea macrophylla variegata in shade (in USDA zone5) and although it had only zero to three blooms each year, I absolutely loved the foliage in the shade. It was in a protected spot (surrounded by trees and fence) with adequate moisture and the foliage looked beautiful all season until fall -- it really was a bright spot in the shade. I also grew variegated redtwig dogwood in the shade, and it was very nice, but the hydrangea really stood out for a small shrub (about 3' high).

Another favorite that I forgot to mention is my variegated Kerria Japonica. It has a light airy shape and beautiful yellow flowers in the spring.

Variagated Elderberry is a sprawler, but looks great in part shade. I find that too much variagation in a border can happen quickly, especially with varigated groundcover.

Rhodedendron and Camelia are rewarding in shade, and come in many varieties. They are so hardy I think they must be at least considered.

I like a lush mixed border, with striped Hosta & varigated Iris foliage to stand out near a mass of red-striped Persicaria Virginiana, and in front of that, the natural light of yellow-flowering Rue, with a native Bleeding Heart, and Coral Bells for satisfying flower color contrast in Spring. A front border of Johnny Jump ups will shade soil so it stays moist, and all grows lush with happy roots. There is also a light colored shade sedum one can try for under shrubs and trees...and a lighter-hued Scotch moss.