Can form data be editable?

I have made a custom permission “flamingo” using the User Role Editor plugin. I have also removed the map_meta_cap filter and added a custom one, like this:

remove_filter( 'map_meta_cap', 'flamingo_map_meta_cap' );
add_filter( 'map_meta_cap', 'mycustom_flamingo_map_meta_cap', 9, 4 );
function mycustom_flamingo_map_meta_cap( $caps, $cap, $user_id, $args ) {
    $meta_caps = array(
       'flamingo_edit_inbound_message' => 'flamingo',
       'flamingo_edit_inbound_messages' => 'flamingo',
       'flamingo_delete_inbound_message' => 'flamingo',
       'flamingo_delete_inbound_messages' => 'flamingo',
       'flamingo_spam_inbound_message' => 'flamingo',
       'flamingo_unspam_inbound_message' => 'flamingo',
       'flamingo_edit_outbound_message' => 'flamingo',
       'flamingo_edit_outbound_messages' => 'flamingo',
       'flamingo_delete_outbound_message' => 'flamingo',
);

$caps = array_diff( $caps, array_keys( $meta_caps ) );
if ( isset( $meta_caps[$cap] ) )
    $caps[] = $meta_caps[$cap];
    return $caps;
}

Users that have “flamingo” permission can view all inbound messages, but I want them also to be editable. Is this possible? Not sure if I’m doing something wrong or if maby I’m asking about a feature that not exists.

Thanks in advance for helping me.