Insert script

In almost all cases it is sufficient to have these custom scripts in the footer – sometimes it is necessary to set a priority for these inserts. But for all jQuery scripts, they must be loaded after jQuery is already loaded.
( maybe your timing is a bit to fast – i did not test your script – but if 100 does not work try 300)
( PS – this comes to child-theme functions.php )

function your_custom_script_insertion() { 
?>
<script type="text/javascript">
(function($){
	$(window).on('load',function(){
	setTimeout(function(){
		var _hash=window.location.hash;
			if(_hash){
				var targetElem=$(_hash);
				if(targetElem.length){
					targetElem.addClass('highlighted-term');
				}
			}
		},100);
	});
})(jQuery);
</script>
<?php 
}
add_action('wp_footer', 'your_custom_script_insertion');

However, I do not understand the meaning of the script.
because only if you click a link with hash, the hash is also indicated above in the Url. If you click several hash links, then all get this class one by one.