I have been continuing to work on socialization with Shyla multiple times per week. I do some of the training alone, some of it as part of a group class, and some during one-on-one lessons with our trainer. As always, I have no photos of Shyla during our in-town training, so I'll pepper this with photos from our outings in the mountains at home.
Apparently, Shyla's current state is a step in the rehabilitation of a dog who missed her puppy socialization that my trainer sees frequently. The dog finally (8 months later, in Shyla's case) accepts the world for what it is and knows what is normal. So, the dog functions beautifully until "abnormal" things occur - and then the "spook" is quite obvious.
The bottom line is that this change in Shyla is expected and good. Now, we can work on the specific things that Shyla is still afraid of - like men talking on cell phones, women with gravelly voices, construction equipment, skateboards, people squatting down to look in her eyes, etc. She now truly trusts me - so she'll literally look at me when she gets scared. I back her away from the scary thing, until she is at a distance that is comfortable for her, and then we watch the scary thing from a distance, using the principles of BAT (Behavioral Adjustment Training).
I also know that the journey has been incredibly rewarding. My trainer observed that Shyla's bond to me is much stronger than a "normal" dog's bond would be just 8 months after arriving in a new home. I feel very lucky in that regard, for my bond to her is just as strong. She is a gift.