Please see the documentation on Mac's action to replace with regular expression
This shows that a different syntax from the WIndows version is used.
On the other hand: why do you need to swap as I bet that this field is really only used for sorting but the player then shows the contents of the non-sort field.
And that would mean that you don't need the swap but you only have to remove the first part of the name (or the "the"). I doubt that you really need the full name for sorting.
And this leads to the next advice: why use complicated and apparently incomprehensible expressions if the purpose does not require it. Keep it as simple as possible, would be my motto.