Regarding the Portuguese translation (here's a direct link of the relevant text, the substack author claims "I would say that this is at the level of a human expert"; frankly, that is not what I'm seeing.

(NB: I'm a Portuguese native speaker, and I'm somewhat used to 1500~1700 Portuguese texts, although not medical ones. So take my translation with a grain of salt, and refer to what I said in the comment above, test this with two languages that you speak, I don't expect anyone here to "chrust me".)

I'll translate a bit of that by hand here, up to "nem huma agulha em as mãos.".

Observation XLIX. Of a woman, who for many years administered quicksilver ointments professionally, and how quicksilver is a capital enemy of the nerves, somewhat weakening them, not only causing her a torpor and numbness through the whole body, but also a high fever; and, as the poor woman relied on a certain surgeon to cure her, he would bleed her multiple times, without noticing the great damage that the bleeding did to the nerves, especially already weakened ones; but while the surgeon thought to be keeping her health through bloodletting, he gave her such a toll that she couldn't move, not even hold a handkerchief, or even a needle on her hands.

I'm being somewhat literal here, and trying to avoid making shit up. And here's what GPT-4 made up:

• translating "hum torpôr" (um torpor) as "heaviness". Not quite, this mischaracterises what the original says, it's simply "torpor".
• "Reparar" is "to notice". GPT-4 is saying something else, that he didn't "consider" it.
• "Segurar a saúde" is tricky to translate, as it means roughly "to keep her health safe", or "to keep her health from worsening". I've translated it as "keeping her health", it's literal but it doesn't make shit up. GPT-4 translated it as restoring her health, come on, that is not what the text says.

Interesting pattern on the hallucinations: GPT-4 is picking words in the same semantic field. That's close but no cigar, as they imply things that are simply not said in the original.