I have the first English Gollancz edition, and the Giant Spider's health is 20. I wonder if a different English edition gave it 30 health. I didn't see that in any of the "patch notes".
I have a question about the change to the hydra's "Many heads" (section 350). It seems to be only a small wording change with no functional difference that I can see. "The third combat round" is changed to "three combat rounds", "back to full health" was changed to "up to full health", and "fourth round" was changed to "fourth combat round". Is that the extent of the change? Is there any functional difference to the change?