Just want to report back; with the help of an EE engineer, the problem has large been resolved.

Vast majority of the information was recovered without a problem. A few glitches existed due to some incomplete copying of some file structures.

The original problem seemed just to be a one-off error that occurred very rarely in the 1.11 build, which should not be normally expected. When we tried it a second time on the exact same sd card all other conditions being the same, the move process completed without an issue. So as long as the library content and settings are backed up in the future, there shouldn't be a problem with anyone trying perform the move.

Thanks again to Dr. T, kenjennings, and sjerrel for the helpful hints. And I have to say that the customer service of Entourage has been impeccable so far, better than any other company that I have dealt with.