I have an ACF form in post edit with Range type generated by PHP (local field no DB usage).

So, to store input values i’m using custom meta field. At this moment I can’t find an easy way to alter data in DB after post updating. ACF documentatin demonstrates how to get new values after post update.
add_action('acf/save_post', 'my_acf_save_post');
function my_acf_save_post( $post_id ) {
$values = $_POST['acf'];
// Check if a specific value was updated.
if($values && isset($_POST['acf']['...'])) {
update_post_meta($post_id, 'test_field', $_POST['acf']['...']);
}
}
$_POST[‘acf’] data looks like this:

The only way to get field value is to specify the key ID of the field.
The main problem is that initial field key doesn’t match with $_POST[‘acf’] key!
Initial key Id obtained with acf function:
acf_get_local_field('test_field');
