This question might be off-topic here, but concerning English usage.
We are translating some illustrated book for kids about astronomy, and then have a question as in the title.
Referring to Wikipedia etc., It appears that "binary stars" represents the star systems of two stars, whereas "multiple stars" does those of three or more stars.
Thus, our question is whether it is an abuse to use "multiple stars" for binary stars.
Simply, we don't know what to translate "multiple stars" into Japanese, because there is no one-to-one counterpart of words in Japanese.
Thank you in advance.