Yes, people can make cards in many foreign languages. There have been AwesomeBoxes made in Japanese, Chinese, Hebrew, Arabic, Russian, and many other languages with different character-sets than English.
However, there is occasionally an unusual character that can make a card render improperly. Sometimes it's a foreign-language character, and other times it's a new type of Emoji. If you see this happen on your AwesomeBox, just contact us and we'll fix it.
Also, sometimes, but rarely, an unusual character will trigger an error when the box is submitted for manufacturing. Contact us immediately if you don't get an automatic email from us the day after your deadline saying "(Recipient's) AwesomeBox is Done!"
Other helpful FAQs: