Looking at the forums it appears that the Gallery Sort should determine the sort of search returns.
This is not the behavior I get. My images are sorted by a custom sequential number in the location field within each album, but this does not seem to have any bearing on the sort either.
So when a user clicks on a Tag that returns 500 images the sort seems completely random.
Tried various custom sorts in the gallery settings, with nothing seeming to effect the search returns.
Wouldn't mind being able to set a custom sort like "date,filename" Ascending - for searches while retaining custom sort for albums.