If you want to modify values as shown here
$_POST['acf']['field_60526244663f2'] = $new_calc_collected_from_other_sources;
so that acf uses these values when it updates fields then you need to use a priority in your add_action() of < 10 so that it happens before ACF saves values.
add_action('acf/save_post', 's4f_save_post_step_content', 1);
Once ACF has updated values at priority 10, altering the contents of $_POST['acf'] will have no effect.
