i'm confused as to what purpose the numbers 2 and 1 serve in "Replace string: $2 $1"? i don't see any explanation of that under the help file, Replace with regular expression section.
No, if you insist on the "etc.". As language is not logical you will not be able to create a universal action.
It would be easiest to create several action, each dealing with one of the words separately.
Or you have a set of actions which deals with those artists first that have something following the "the" and then one that deals with those that have not.
Search string for the first variation (which will process only those strings that have something behind the ", the":
^(.), The (.)$
Replace with:
The $1 $2
This action leads to a string that has no ", the" in it, so that the second action will not do anything.
The second:
^(.*), The$
Replace with:
The $1