Issues with Post Title Generation Using Custom Table Data

We are using the Metabox plugin, specifically the MB Custom Table extension, to store custom data in a custom table (wp_person). The goal is to automatically generate a post title for a custom post type (veranstalter) using two custom fields, person_vorname and person_nachname, stored in the custom table.

Current Setup:
1. We have a custom post type called veranstalter.
2. The custom table wp_person contains two fields: person_vorname and person_nachname.
3. The title for the veranstalter post should be generated by combining the values of person_vorname and person_nachname from the custom table.
4. The table is properly set up and data for person_vorname and person_nachname is available, but there is an issue with retrieving the data and updating the post title.

The Issue:
• We are using the save_post action hook to retrieve the values from the custom table based on the post ID and then try to update the post title.
• However, the data is not always being retrieved correctly, and we are encountering errors like “No data found for post ID” or “First name or last name is empty.”
• We also tried adding delays and checked if the custom table data is accessible using raw SQL queries, but the issue persists.

Our Code:

add_action('save_post', function ($post_id) {
    // Safety checks to prevent unnecessary or repeated executions
    if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) {
        return;
    }

    if (wp_is_post_revision($post_id)) {
        return;
    }

    // Check if the correct post type is being saved
    if (get_post_type($post_id) !== 'veranstalter') {
        return;
    }

    // Prevent recursive calls by using a flag
    static $is_updating = false;
    if ($is_updating) {
        return;
    }

    // Retrieve custom field data from the custom table
    global $wpdb;
    $table_name = $wpdb->prefix . 'person';
    $sql = $wpdb->prepare("SELECT person_vorname, person_nachname FROM $table_name WHERE ID = %d", $post_id);
    $result = $wpdb->get_row($sql);

    // Check if the data is found
    if ($result) {
        $vorname = $result->person_vorname;
        $nachname = $result->person_nachname;

        // Only generate title if both fields have values
        if (!empty($vorname) && !empty($nachname)) {
            $is_updating = true; // Set flag to prevent recursion

            // Generate title from Vorname and Nachname
            $title = trim("$vorname $nachname");

            // Generate a unique slug for the post
            $unique_slug = wp_unique_post_slug(sanitize_title($title), $post_id, 'publish', 'veranstalter', 0);

            // Update the post title and slug
            wp_update_post([
                'ID'         => $post_id,
                'post_title' => $title,
                'post_name'  => $unique_slug,
            ]);

            $is_updating = false; // Reset flag
        }
    } else {
        // Log if no data is found for the provided post_id
        error_log("No data found for post_id $post_id in the custom table.");
    }
});

Our Question:
• Is there a recommended approach to automatically update the post title using custom table data in Metabox?
• Are there any other solutions or workarounds for this type of situation?
• Is there a way to ensure that data is reliably retrieved and the title is updated without issues?

We would appreciate any advice or insights on how to solve this issue more effectively.