Don't worry, we send this information to staff and every so often, they will go through our list and fix it so that both homophones are accepted. Eventually the audio will be restored for this exercise. :-)
Nope, the oversight was made by a native English speaker. Different English speaking regions and countries use different terms for the same thing. "Swimming suit/bathing suit/swimsuit" are all used in American English, costume is not. Now added, thank you!