Frustrating for both you and Savannah, I'm sure, as you've done so much to help her get better. Because Savannah is PPID/IR all discussions regarding her should remain on the main group - including hoof ones. Please post a quick note on the man group that includes a link to her photos and I can take a look for you.
Her frogs aren't wider and healthier because she isn't landing heel first, so isn't developing them. They are narrow and long because they have migrated forward with the rest of the foot. The white line is a seam between the wall laminae and the sole which you can't see looking from the front. What you are seeing is likely part of the laminar wedge material. If you can see something that looks like the white line, it's possible the sole has been pulled forward and up by the laminar wedge in the toe.