While "Panchito" is a common nickname in Spanish-speaking countries, it's not as widely understood or used in English. It's important to note that, due to cultural differences, using the nickname "Panchito" in English might be seen as informal or even disrespectful, especially if you're not close to the person you're addressing.
It's always best to use the person's preferred name or a more formal address like "Mr./Ms. [last name]" or "Sir/Madam" unless you are specifically invited to use a nickname.