回答
This is not a piece of advice to you I'm talking to myself for my practice of writing skills.
the fact that you're in trouble tells me, the thought 'In Japan the number eight is considered to be an auspicious number' has come to be already suspicious. when I see the car-number '8888', I'd wonder the driver might be an ordinary person. at any rate if you would like to put the phrase into your sentence, I suppose it'd be better for you to say ' in China' instead of 'in Japan'.
:Why is the number 8 considered lucky in Japan? - Reddit.
https://www.reddit.com/r/japan/comments/5r2g1f/why_is_the_number_8_considered_lucky_in_japan/
:Lucky Numbers in China.
https://www.travelchinaguide.com/intro/social_customs/lucky_number.htm
:What Are the Lucky Numbers in China? .
https://www.topchinatravel.com/china-guide/what-are-the-lucky-numbers-in-china.htm
この質問に回答する
「日本では数字の八は、末広がりの形をしていることから縁起の良い数字とされています。」の訳にに手こずっています。特に「末広がり」の部分はどうしたら外国人にイメージをもってもらえるかがカギだと思います。宜しくお願いします。