How did you get the last two? The best-hidden ones? I've done this game a few times and still it's 86% for me. The only room I haven't explored is the one requiring 16 lives to pass through.
None are hidden. Try checking the edges of the rooms you've seen for smaller or boarded passages.
Thank you! I looked closer, and here was one unobvious room indeed. I got 100% talismans and even the secret ending.
