I might be missing the point here, but…
<?php
$result_cmb_is_review = get_post_meta($post->ID, 'cmb_is_review', true);
if ($result_cmb_is_review == 'checked'){
include 'inc/template_review.php';
echo '<h3>'._e('Summary').'</h3>';
echo '<p>'.get_field("review_summary").'</p>';
}
Is this what you mean?