@
chaley - not convinced the Tweak is working when a book is added (but I might have missed/forgotten something), following is a composite image of the Book List, Tweak (copy method is 'invert'), and Manage Authors list:
Note: 'van' is in the default list of surname prefixes, and I've added 'St.'
The following are: a) changing the Author Sorts to what I would have expected them to be, and b) the Book list after resorting
The edit pencil in Manage Authors needs to lighten up a bit
BR