[chaley]

I think this does what you want. The trick is to loop through the characters. Your template operated on only the first character in the list.

program:
	result = '';
	if $#chars then
# Loop through the characters adding the universe prefix
		for char in '#chars':
			result = strcat(result, first_non_empty($#universe, $series, $title), '.', char, ',')
		rof;
# Clean up the list, adding spaces and removing the trailing comma
		result = list_union(result, '', ',')
	fi;
	result