The Indonesian text does not translate to 'my older brother' since that would be 'Kakak saya'. The text as it is translates to 'The or an older brother fell...'
There is no indication that the "kakak" in the Indonesian sentence is someone's older sibling. Therefore, "The older sibling fell from his bed." should be accepted.
I answered 'Older sibling fell from his bed' and this was wrongfully accepted. There should be an article in front of Older, else it makes no sense (unless maybe as the headline of a 'fait divers' in the newspaper)
"Older brother fell from the bed" should be fine?