zentao/extension/ipd/todo/ext/lang/en/zentaomax.php

<?php
$lang->todo->typeList['review']      = 'Review';
$lang->todo->typeList['issue']       = 'Issue';
$lang->todo->typeList['risk']        = 'Risk';
$lang->todo->typeList['opportunity'] = 'Opportunity';
$lang->todo->typeList['meeting']     = 'Meeting';

$lang->side->opportunity = 'Opportunity';