I’m a little lost by your question. Is the taxonomy selected using the standard WP taxonomy meta box or is the term only selected in an acf taxonomy field?
If the term is selected using the standard wp taxonomy meta box then the value selected will be passed to your match function in the $screen arguments. Sorry, it has been a long time since I’ve created location rules and all of my examples use the old method.
If there the term is set with an acf taxonomy field then it is more difficult because the values of other fields are not sent in the ajax request.
