I would like to know if it is right to translate the names of countries or cities in official legal documents. For example, should I translate the name of the Italian city of Torino into English as Turin, or should I use the official Italian name?
Based on actual knowledge and personal experience, it is not just right, but also required that most foreign documents intended to be submitted to (at least) US and state governments and agencies must be translated into English- including place names. There are only a few exceptions to this rule (passports being one). The standard is generally to have the English equivalent alone or the English equivalent with the original foreign name in parenthesis or some other punctuation.
You didn't state what was the document to which you referred nor the intended agency. But whatever the cases may be, you should check with the intended agency and they will tell you their policy on which documents have to be translated and under which standard.
Hope this helps.
If you are in the US, you should be able to get the correct answer by calling a legal aid office. Here is a link to the Legal Services Corporation where you can search for legal aid offices. Or use this Google link to find legal aid in your area (if Google knows where you are, which they usually do). Depending upon your situation, you might be able to get free help with your legal document.