Hello,
IT's true that there was a minor error in 1.3 release where SalesOpportunity would fail to add the field to tasks RecordSet. The fastest way is to add the following code at the end of modules/Premium/SalesOpportunity/SalesOpportunityCommon_0.php (one line before the closing ?> tag):
Utils_RecordBrowserCommon::new_record_field('task', 'Opportunity', 'select', true, false, 'premium_salesopportunity::Opportunity Name;Premium_SalesOpportunityCommon::crm_opportunity_reference_crits', '', false);
After you see the field appear in Tasks, you can remove that line.
I apologize for the inconvenience caused.
The translation tool can be found through Menu->Administrator->Language & Translations, you can find the label you'd like changed there and simply click on it and enter new string.
Kind regards,
Arek