"The people dance hula in the spring in Hilo."
Translation:Hula ka poʻe i ke kau kupulau ma Hilo.
A wonderful thing about Hilo is its very narrow range of temperature. In December the lowest average is 65°F/18°C, and in the height of the July it’s around 83°F/28°C. Due to this limited range, most homes deem air conditioning an expensive luxury, if they have it at all. And central heating simply does not exist in Hilo.
Hilo has an average 126.69 inches of rainfall a year
Actually "ma Hilo" and "i ke kau kupulau" could grammatically be in either order with the one mentioned first usually being considered a bit more important for some reason. But this probably won't be accepted for this lesson because it doesn't follow the English.
Another reason it might not be accepted is that if you put "ma Hilo" first, it sounds more like it's saying that all the people in Hilo dance hula in the spring. But I'm sure it's making reference to the Merrie Monarch Festival which is held every spring (except this year, of course) in Hilo, so--in this case--"ma Hilo," which is the locale of the hula competition, should come at the end to avoid confusion.
This is a case of something that may be grammatically correct might change the meaning of a sentence.