There are few forgotten inventions, and none that we might truly care about 🍈
"So much so that people sometimes claim that the Egyptians and the Incas used some kind of now-lost technology. But they most likely didn’t: they were just really good at cutting stone." This and the other examples "just really good" doesn't make sense. It's basically handwaving and begging the question.
Good in such craftmanship means they had developed techniques (doesn't have to involve new tools or technology in the sense of an invention: specific moves, or specific way or applying existing tools still quality) that a modern expert on those areas doesn't know how to replicate.
"We don’t really know how the ancient Indian metallurgists did it, which means it could be an actual lost technology. Or maybe they just got lucky."
Again, hardly probable. It's obviously this wasn't their first rodeo, or rather first steel coated using this technique. If they got lucky at some earlier point making steel columns and landed at the technique, it still qualifies as a lost technology, since they knew the technique and we don't. Many of our mordern technologies are also discovered by accident, doesn't mean they're not technologies but "luck".
Such an interesting read! I'm saying it again--you should write a book. I wish I had the energy to research things with such meticulousness and passion.