Why does all that have to be done with ADD?
That over complicates the process to (safely) handle all the edge cases.
'Auto-incorrect' comes to mind when slam-bam fixing is employed. Take time and do it per book---once (
leave a note in comments about (reason for?) fails so you don't keep wasting time and again on that book. You will also learn ways around/causes that may cause this to happen. A straight Get Metadata may not be the way (I do a lot of copy from other sources and past into the proper places in the MDE)
Bulk mode (2 or more books selected) MDE:
Search and replace to fix various field values
Use of the various ticks for other common(ish) tasks
Swap fields, compute sorts, extract covers...
Use the
Quality Check Plugin to Find lots of Metadata issues and the Fix section to fix Author format data issues
Use the
Tag Browser (sidebar) (
Manage for major correcting sessions) to fix case or spelling issues (the tag browser edits the linked lookup values used in the MDE. Fix it there and all existing uses get fixed. Fix it in the MDE and only selected get fixed.