Example of how to change the return to event list button displayed on the cart modal based on the terms set the event the ticket submission is for.

tw_ee_mer_change_event_list_url_from_term.php

<?php // Do not add the opening PHP tag if you already have one.

function tw_ee_mer_change_event_list_url_from_term($default_event_list){
	// Check if this is an ajax request.
	if (wp_doing_ajax()){
		// Check we have an event id.
		if (!empty($_POST['tkt-slctr-event-id'])) {
			$EVT_ID = absint($_POST['tkt-slctr-event-id']);
			if (has_term( 'courses-seminars', 'espresso_event_categories', $EVT_ID ) ){
				return 'https://domain.com/courses-seminars/';
			} elseif (has_term( 'summerschool', 'espresso_event_categories', $EVT_ID ) ) {
				return 'https://domain.com/summer-school/';
			}	
		}
	}
	// Return the default event list url.
	return $default_event_list;
}
add_filter( 'FHEE__EED_Multi_Event_Registration__set_definitions__events_list_url', 'tw_ee_mer_change_event_list_url_from_term' );