The solution was to create a custom JS variable that when the image was clicked on would find the "c-card c-card--primary c-parkcard " div (9 parents up) and then go back down to find the h3 element by class and then return the text:

function(){
var z = {{Click Element}}.parentNode.parentNode.parentNode.parentNode.parentNode.parentNode.parentNode.parentNode.parentNode
.getElementsByClassName('u-h6 c-card__title')[0].innerText;
return z;
}

use of getElementsByClass is as simple as:

$dom = new DOMDocument('1.0', 'utf-8');
$dom->loadHTML($html);
$content_node=$dom->getElementByClass("c-card__body");

$div_a_class_nodes=getElementsByClass($content_node, 'h3', 'u-h6 c-card__title');

You have set "h3" as "attribute name. "h3" is not an attribute (but the name of the tag). You do not want to set an attribute name at all, because you do not want to return the value of an attribute, but the innerText of the tag, and that is the default behaviour anyway.

If you use a DOM variable this will return the first instance on the page. If your selector matches several DOM nodes, you will still just get the first one, regardless if what the user clicks. If you expect this to update depending on the clicked element, you should rather use the {{Click Text}} variable (a built-in variable that you might have to enable first).

Chances are that the actual click element is not the h3, but the nested link inside, but that does not really change things for you (as in both cases the innerText will be the contained texted nodes, which in this case is the same).