This must happen to be a subject that bothers me. Years ago, when the words crêpe(s) and gâteau came into use in the UK, they came with the circumflex. They are loanwords, so they do not change. However, there has apparently been influence from the US to drop the circumflex. This is wrong or plain lazy. Duo counts crepes as the 'translation' of crêpes. There is no such word as crepes ...... at least there never used to be. An error is being turned into a word. Please stop your part in this Duo, by accepting both forms of the English. This is simply in recognition that both forms are now in use but 'crêpes' seems to be a problematic word for some English speakers, despite now being an English word,- a loanword.
American English drops all accent marks on words from other languages. If you pay attention, so much of French words in the English language have dropped the accent marks. Not just crepes. It is not an error when your language has adopted the word, with variations. French has done it with its words taken from the original language the language tree romance languages grew from.
This is how languages change and evolve. Always have.