Remap Visual Composer 4.3.x and newer CSS column class names back to legacy class names

vc-legacy-class-remap.php

<?php
/*
Plugin Name: Visual Composer Legacy Class Remapper
Description: Remap Visual Composer (4.3.x and newer) CSS column & row class names back to legacy (4.2.x and older) class names
Version: 1.0.0
Author: Milo Jennings
License: GPL2
Plugin URI: https://gist.github.com/1b0b602432175937f658
*/

// Filter to replace default css class names for vc_row shortcode and vc_column
add_filter( 'vc_shortcodes_css_class', 'custom_css_classes_for_vc_row_and_vc_column', 10, 2 );
function custom_css_classes_for_vc_row_and_vc_column( $class_string, $tag ) {
  if ( $tag == 'vc_column' || $tag == 'vc_column_inner' ) {
    $class_string = preg_replace( '/vc_col-sm-(\d{1,2})/', 'vc_span$1', $class_string ); // This will replace "vc_col-sm-%" with "vc_span%"
  }
  $class_string = str_replace( 'vc_column_container', 'column_container', $class_string ); // This will replace "vc_column_container" with "column_container"
  return $class_string; // Important: you should always return modified or original $class_string
}