You could try the following below:

var input = document.evaluate("//li[text()='ATACAMA']", document, null, XPathResult.ANY_TYPE, null );

var thisregion = input.iterateNext();
thisregion.click();

So I don't have a clue about Xpath, but like you said, there is nothing stopping you from using querySelector or in this case querySelectorAll instead.

Here I create an array of all the li elements and use .find to get the element that has the text "Item 3" in it. I then click the element programmatically. All of the li elements have onClick event inline in the html.

Would this work for you?

let li_item = Array.from(document.querySelectorAll('li'))
              .find(x => x.textContent === 'Item 3');

li_item.click();

function select(element, n) {
  element.style.color = "red";
  console.log(`${n} has been selected!`);
}

<ul>
  <li onClick = "select(this, 1)">Item 1</li>
  <li onClick = "select(this, 2)">Item 2</li>
  <li onClick = "select(this, 3)">Item 3</li>
  <li onClick = "select(this, 4)">Item 4</li>
  <li onClick = "select(this, 5)">Item 5</li>
</ul>