Being a proud Scotsman, I wrote "Irn Bru is braw". I know it's not technically "English" but in this particular context I (partly with tongue in cheek) think it should be accepted... Because Irn Bru IS braw. It's the most accurate way to describe the lovely nectar.
Braw is definitely the right term to use for a stereotypically Scots (as opposed to Gaelic) product. We have been using the word since long before the Gaels arrived from Ireland. We know this because it is almost identical to the Welsh braf (f is pronounced /v/ which is interchangeable with /w/) and identical to the Breton. These are essentially the language we spoke before people came over from Ireland. The Gaelic word brèagha (gh pronounced as a y, which you would not expect here) is not nearly as close. There is a very long argument about whether it is the same word on this page but it certainly resembles it and has acquired some of the same meaning. D
Is there a reason why the name of the drink is spelled in capital letters?
Edited 14/8/20: when I wrote this their website said Irn Bru. Now it says IRN-BRU.
It isn't the standard spelling. The spelling used on their own website is IRN-BRU. So Duolingo should change to IRN-BRU.
There is also confusion because on their packaging the hyphen is always replaced with some graphic that people do not realize is a hyphen.
Almost. It is IRN-BRU. The comments and pictures on this page show that the do their best to disguise the hyphen, which is why lots of people are convinced there is no hyphen. Judging from this comment which I had to edit I think they may have changed their own official spelling some time last year fron Irn Bru.
That's completely true. But in fact they would put a vowel in even if it wasn't there originally. See https://forum.duolingo.com/comment/37138871?comment_id=37280510