2.78 has a cane and a beard

(btw Kovid never updates past Major releases.)
Calibre is an RDB, the case change is written into 1 location (Authors table), The Books Table use the Index value from the Authors table. No change for all existing, 1 new entry for the currently being imported book.
It is unfortunate, that calibre updates ANY fields case. But, that is the way it works, from almost day one.