Shouldn't 형제 be translated to 'older brothers' since 형 alone means 'older brother'? I got it wrong because of that
No, don't be misled by '형' in the word; 형제 is the generic term for a brother without any connotation of age differences. In fact, 쌍둥이 형제 means "twin brother"! 형제 is also the word used when talking about other people who are not related to you, e.g. 그들이 형제다 = They are brothers.
Also, 형제 (兄弟) is a Sino-Korean word. To break it down, 兄 = older brother, 弟 = younger brother.
I think this whole lesson lacks enough context in each question for us to get the right answer straight away. What's wrong with Older brother?
Because 형제 is the generic term for 'brother' without any connotation of age differences.
Here it's assuming that the "ours" is masculine or masculine-majority, right?