That is because the template is sending the following author name, just as you told it to:
Code:
Feist, Raymond E. - Chaoswar Saga - 1
Now take a look at what happens when you transform that from LN, FN <--> FN LN.
The Kindle automatically switches LN, FN to FN LN in the display field, and uses the LN section for the sort values. (MOBI/AZW3 does not have a separate author_sort and author field.)
Some people have gotten around this by using {author_sort:'re(",", "_")'} but you will sacrifice the ability to sort based on author names.