They'll qualify their answers in English but as the article mentions, if your prompt asks for a confidence score, that "uncertainty" doesn't translate into low numerical confidence.

Quantifying their own confidence is also something they're not good at, and which the format would prevent them from refusing to do or preceding with a caveat if that's what you'd want of them. Particularly since the response format seems backwards - giving confidence, then carbs estimate, then observations/notes, rather than being able to base carbs estimate off of observations/notes and then confidence estimate off of both of those.

> They'll qualify their answers in English but [...]

That the default user-facing chat as a normal user would use it gives a warning is the key part IMO. I don't think expectations of there being no "wrong way" to use the model can necessarily extend to API usage with long custom system prompt and restricted output format.