I've discovered a few more things.

If you already called someone "big sister" or "big brother" originally, it seems the AI doesn’t force you to use different terms. There’s no sudden repetition like “Rui Big Sister Big Sister” or “Kaiser Big Brother Big Brother.”

So if you start by calling someone “hyung” or “senior brother,” the AI doesn’t feel the need to change it.

It seems the AI’s judgment is that “a little sister who calls her big brother ‘hyung’ is also cute.” An unusual taste, but some would call it “refined appreciation.”

“The rules are simple. Just escape from …