I'm Japanese, and I can still usually spot AI-generated Japanese by its word choice. Some words, like 実務 (practical work) and 帳簿 (a ledger), turn up far more often than they should. Casual ones like 効く (to work well, to be effective) and 刺さる (to pierce > to resonate, to hit home) get used where another word would normally be the first choice. They're the Japanese equivalent of "delve."

I'm not a native English speaker, but my impression is that AI-generated English has improved a lot recently and is harder to pick out than it used to be. Does that match what English native speakers see?

What about other languages? Chinese must be one of the most heavily trained languages, so I'd expect it to have improved as much as English. And what about Spanish, Hindi, and other widely spoken languages — can speakers still tell?

Also, I think which model you use still matters far more once you leave English. One of my first singularity moments came from Gmail's AI drafting feature. It had clearly absorbed the conventions of Japanese corporate email culture, bureaucracy and all.

These days, Anthropic's Opus 4.6 (and Fable 5 outside coding sessions) writes reasonably good long-form Japanese, and Google's models hold up across a wider range of registers. OpenAI's models, Opus 4.8/5 and Fable in a coding session sound way too geeky.

Curious to hear your thoughts.