Translation:When is his birthday?
The question was, "when is his birthday?" The question did not use 几点 to ask for what time or hour. It asked 什么时候 or "when", right?
In English, "when" can mean any frame of time; such as next week, tomorrow, in October, this summer, or even a specific date. Does 什么时候 work the same way as in English?
According to the link below, 什么时候 can be used to ask for a date:
Wáng Lì: Nǐ shénme shíhou jiéhūn?
王 丽：你 什么 时候 结婚？
Wang Li: When will you get married?
Zhāng Wěi: Bāyuè shíjiǔ hào.
张 伟：八月 十九 号。
Zhang Wei: August 19th.
I have seen comments from other native speakers saying 什么时候 is often used at the beginning of the sentence. If it's wrong to use it at the end, DuoLingo should update the Chinese phrase.
My reply @grippygecko was because they believe 什么时候 is used to ask a question only about time and not about dates.