wecr_restricted_content_message_cant_reply.php

<?php
/**
 * Allows you to filter the stock bbPress message that reads 'You cannot reply to this topic:'
 * 
 * @param string  $message      stock Easy Content Restriction message
 * @return string               Your custom message
 */
function  change_cant_reply_message( $message ) {
  return 'Our custom message';
} 
add_filter( 'wecr_restricted_content_message_cant_reply', 'change_cant_reply_message' );