This script doesn't do anything you couldn't already do manually, but does put the whole process into a single script. Search Artists to Make Sort Artist will search for tracks whose Artist tag contains a user-entered search string. It will then ask you for a text string to use in each of those tracks' Sort Artist Tag. Or, rather than have the script automatically enter a Sort Artist, you can choose to display the results of the search in a new playlist to inspect them, then use Batch Set Tracks Sorting Tags to set the Sort Artist tag of just the selected tracks. FWIW.