I'm going to take a little different tack on this task.
When asking about parsing text one should always provide adequate samples of the before and after conditions of the text.
one and two
Desired Outcome 01:
two and one
Sample 02 (selected text highlighted):
Some text one and two
some more text.
Desired Outcome 02:
Some text two and one some more text.
I've added a starting sample to my macro, so user's don't have to monkey with providing it themselves and possibly make a mistake.
Since this is a simple find/replace task I've elected to use the Search and Replace Clipboard action.
I've also chosen to make the regular expression more precise (for better or worse).
Since you'll always know the initial condition of your selected text for this particular macro, there's nothing wrong with your regex – but there can be unintended consequences when using greedy quantifiers like
See my regex explained on RegEx101.com.
As you can see I'm also pasting the result text instead of typing and deleting the past clipboard – these are techniques worth noting.
For learning regex I like the following tools:
Swap Words 1 and 3 of 3 v1.00.kmmacros (5.8 KB)