When printing a label through Shiptheory for FedEx, you may notice that some labels have jumbled or illegible text on them, causing the name/address on the label to appear like this:
This is caused by having foreign characters in your order, as FedEx doesn't support foreign characters. Sending items internationally is of course supported, but you'll need to translate the address to the Latin Characters accepted by FedEx.
For example, if sending to Tokyo and the address was under "東京", then it'd need to be changed to "Tokyo" and then rebooked.