Code snippets:

FWIW: your #authors_namesinverted column can be better expressed as
  {authors:'list_re_group($, ' & ', '.', '(^.*$)', '[[$:swap_around_comma()]]')'}
or as I would prefer:
  program: list_re_group($authors, ' & ', '.', '(^.*$)', '{$:swap_around_comma()}')

And unless you have a reason to have two columns I would do this to build the inverted comma-separated list directly from the authors column:
program:
	res = '';
	for author in $authors separator ' & ':
		author = swap_around_comma(author);
		if !res then
			res = author
		else
			res = strcat(res, ', ', author)
		fi
	rof