Нужна помощь!

на вскидку не скажу, вот пример немного другого:

add_shortcode('brand_condition_complect', 'json_brand_condition_complect');
// json brand condition complect
function json_brand_condition_complect(){
	$pages = get_pages(array(
		'parent'       => 16,
		'sort_order'   => 'ASC',
		'sort_column'  => 'post_title menu_order',
	) );
	$brand = Array();
	foreach( $pages as $page ) {
		$brand[] = esc_html( $page->post_title );
	}
	$condition = Array();
	foreach( get_terms( 'pa_sostoyanie', ['hide_empty' => false] ) as $term ) {
		$condition[] = esc_html( $term->name );
	}
	$complect = Array();
	foreach( get_terms( 'pa_komplektacziya', ['hide_empty' => false] ) as $term ) {
		$complect[] = esc_html( $term->name );
	}
	$date = array();
	for( $i = (int)date('Y'); $i >= (int)date('Y') - 40; $i-- ) {
		$date[] = $i;
	}
	$brand_condition_complect = array(
		'brand' => $brand,
		'condition' => $condition,
		'complect' => $complect,
		'date' => $date
	);
	ob_start();
?>
<script type="text/javascript">var formSelectData = <?php echo json_encode( $brand_condition_complect ); ?>;</script>
<?php
	return ob_get_clean();
}

и jQuery скрипт заполнения селекта с CF7

jQuery(function($){
	// fill a selects
	if(window.formSelectData){
		$.each(window.formSelectData, function(name, value){
			var $select = $('select[name$="-' + name + '"]');
			$.each(value, function(n, val){
				$('<option>').val(val).text(val).appendTo($select);
			});
		});
	}
});