I am sure you lost most of the feeder roots with the transplant. Whats left is doing its best to keep the foliage turgid while adding new feeder roots. Don't let up keeping the soil moist, but I would not feed it until it stabilizes. Al

Without a doubt, pieris can be finicky, even when they're in an ostensibly "perfect" location. How much more sun is it getting in its new location? They really don't want all that much sun, although in the Bay Area I'm sure they can take more than they would down here. Dappled sun under a high canopy tree is about right. What did the roots look like when you dug it up? What do the leaves look like now?

The leaves are ok, but not happy looking. The roots looked ok, but had not put out any new roots. The plant popped right out, I can remove it with one hand without even trying to pull it. The roots did not look rotten. They are white and healthy looking otherwise.

The fact you can pull it up easily indicates the roots are not established in your soil, even in the sandy part of San Francisco. To establish in your soil will take at least a year, give it a chance. Al

It is actually in half dappled shade with a small ginkgo tree nearby, which is starting to leave out. It looks better then I removed it from all shade with the possibility of some minor morning sun.

Here is a link that might be useful: photo of leaves

The leaves of your Pieris japonica look exactly as they should for that species. Al

The top leaves are ok, but the ones underneath are all wilted, but you can't see it from the top. The tops leaves are the new growth which is growing too fast and the roots won't grow.