Here is the fixed version of my previous code (@moderators , please delete my previous note )
Returns a more comprehensive array of SOAP Client types as an array
<?PHP
function read_wsdl_types( SoapClient $soap ): array {
    $wsdl_types = $soap->__getTypes();
    $lookup     = array();
    $regexes    = array(
        'atomic' => '/^([\w_]+)\s([\w_]+)$/mi',
        'list'   => '/^([\w_]+)\s([\w_]+)[ {]+([\w_]+)[ }]+$/mi',
        'struct' => '/([\w_]+)\s([\w_]+)[\s{]?([\w_]+)*[\s;}]?/mi',
    );
    foreach ( array_reverse( $wsdl_types ) as $wsdl_type ) {
        $matches = array();
        foreach ( $regexes as $type => $regex ) {
            if ( preg_match_all( $regex, $wsdl_type, $matches ) ) {
                break;
            }
        }
        if ( !empty( $matches[1] ) && !empty( $matches[2] ) ) {
            switch ( $type ) {
                case 'atomic':
                    $name            = array_shift( $matches[2] );
                    $data_type       = array_shift( $matches[1] );
                    $lookup[ $name ] = array(
                        'name'      => $name,
                        'type'      => $type,
                        'data_type' => $data_type,
                        'items'     => array(),
                    );
                    break;
                case 'list':
                    $name            = array_shift( $matches[2] );
                    $type            = array_shift( $matches[1] );
                    $items           = array_shift( $matches[3] );
                    $lookup[ $name ] = array(
                        'name'      => $name,
                        'type'      => $type,
                        'data_type' => $items,
                        'items'     => array(
                            array(
                                'name'      => '',
                                'data_type' => $items,
                            ),
                        ),
                    );
                    break;
                case 'struct':
                    $name  = array_shift( $matches[2] );
                    $type  = array_shift( $matches[1] );
                    $items = array();
                    foreach ( $matches[2] as $key => $item_name ) {
                        $items[ $key ] = array(
                            'name'      => $item_name,
                            'data_type' => $matches[1][ $key ],
                        );
                    }
                    $lookup[ $name ] = array(
                        'name'      => $name,
                        'type'      => $type,
                        'data_type' => $name,
                        'items'     => $items,
                    );
                    break;
            }
        }
    }
    array_walk( $lookup, function ( &$type, $key, $data ) {
        if ( !empty( $type['items'] ) ) {
            array_walk( $type['items'], function ( &$item, $key, $data ) {
                if ( !empty( $item['data_type'] ) ) {
                    $old_data_type     = $item['data_type'];
                    $item['type']      = $data[ $old_data_type ]['type'] ?? 'atomic';
                    $item['data_type'] = $data[ $old_data_type ]['data_type'] ?? $old_data_type;
                    $item['from']      = $data[ $old_data_type ]['name'] ?? '';
                }
            }, $data );
        }
    }, $lookup );
    return array_reverse( $lookup );
}
?>