(using Office for Mac 16.16.15)
printf "hello,world\nNǐ hǎo,shìjiè\n你好,世界\n" > nihao.csv
# or:
# curl -o nihao.csv https://gist.githubusercontent.com/dannguyen/13d5c39d499e4bbec622e055283fbb19/raw/f1c50ced36033b9a3aed36ebbbf0cf8734a98809/nihao.csv
open -a 'Microsoft Excel' nihao.csv
Result:
hello world
Nǐ hǎo shìjiè
你好 世界
Related: https://superuser.com/questions/280603/how-to-set-character-encoding-when-opening-excel