Hi Mitchell,
Thanks for reaching out to our team.
As in the Chinese, Japanes and Korean languages each character counts as two bytes, if you use these double-byte characters in the keyword, the limit would be 40 characters instead of 80. You could also refer to this article about how the double-byte characters count towards the limit.
I hope it helps. Please let me know if you have further concerns.
Regards,
Xiaoming, Google Ads API Team