You can filter accordion content by filter hook as follows

add_filter('accordions_item_body', 'accordions_item_body_18032020', 10, 2);

function accordions_item_body_18032020($accordion_body, $post_id){

    $accordion_body = $accordion_body . ' -<p>Custom text here</p> ';

    return $accordion_body;
}

 

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