Translation:My older brother fell from his bed.
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.
This was painful for me to write in English!
Firstly, if we are talking about our own older brother, we'll usually call him "big brother". I've never heard anybody use "older brother" as a name in the same way that "Dad" or "Mum" or "Grandpa" are used.
Secondly, we tend to have the phrase "fall from bed" or "fall out of bed" in English - notice there isn't any article, any a-or-the-or-his bed, just the word "bed".