Yes, @KenH, I now what you mean - I do a lot of woodwork myself. I was just hoping for an easier answer!
Our floor boards in that room are rather cupped already - they never got a finish applied when the house was built, and it’s an open-air house in the Caribbean and they warped. So I’m not too worried about yet another indentation. And that boards already have “character marks” on them, so I may just leave this there for now! But my DH is going to be furious that someone did this. I’m much more worried about placating him than fixing the floor.
I think it would be a really good story for our housekeeper to tell people during the introductory tour - that the guests lit the coil then fell asleep and the mosquito coil fell on the floor right next to the bed, and it’s a miracle the bedding didn’t catch on fire. It would make an impression on people to be careful, I hope.