hi team indonesia, is there any chance this simple translation could be fixed up?
'musim hujan' in english is 'the wet season', 'the monsoon season' or, less formally, 'the rainy season'. while not strictly necessary here, it's probably more natural to include the definite article 'the' as acceptable in translation too.
'rain season' is incorrect. the closest you would get for a literal translation into english would be 'the season of rain', however that is simply descriptive and not the actual name for the season.