Meta Box

Okay, I think I have done it!!
Long trial and error.
Please give me feedback on whether what I have done is a good idea!
Suggestions for improvements welcome!

I have created a new shortcode my_meta2 and I am calling it like this:
[my_meta2 meta_key="key_topic_1" element="topic"]
[my_meta2 meta_key="key_topic_1" element="obj1"]

In functions.php I have added this code:

add_action( 'init', function () {
  add_shortcode( 'my_meta2', function ( $atts ) {
    $atts   = shortcode_atts( [
      'meta_key' => '',
      'element' => '',
      'post_id'  => get_the_ID(),
    ], $atts );
    $value = rwmb_meta( $atts['meta_key'], array(), $atts['post_id'] );

return $value[$atts['element']];
} );
} );