We noticed that a tile from dream I-13 (Z with 3 lights) was removed from the game per script 131 (starts with 834). I saw another user comment on multiple threads that said it was supposed to be the tile with 2 lights, but from what I've read, they would both be removed. This occurs before unlocking the sign token wisdom card after completing the dream. Is removing the 3-light tile a mistake in the script? That would make it to where we could never use this sign token.
Similarly, in dream I-14, we had a player use an ability to get to tile Y instead of using the Ramshackle Train. When they activated the mysterious door script (479), they chose the option for everyone to get an influence card for free, but it required removing tile Y from the game. We had not revealed card D prior, but out of curiosity, we wanted to see what we were going to lose out on. We noticed a sign token fits on that card. While the script didn't say to remove that card from the game, tile Y appears to be the only way to reveal that card. Are we able to still get this card in a future dream somehow? Or, if we return to the train station as the old dream, are we able to fulfill the sign token by discarding the cards to peak at it?
Maybe you are right, I haven't thought of that as a possible explanation.
I know it's strange to contradict the official response, but, actually, I don't think it's possible to resolve (by the rules) the sign token on Tile I-13 Z with the 3 lights. As you said, the tile is removed from the game before unlocking the sign tokens wisdom card and you won't find the same artwork later in the game. Also, there is another sign token that cannot be revealed normally, in dream I-04 (see this thread for details: https://www.etherfields-secrets.com/forum/official-faq/mistakes-in-2-dreams
As for your 2nd paragraph: There are a lot of sign tokens that you may miss depending on your choices during the game. It is not clear on the sign tokens wisdom card if you can resolve a sign token by using the "Peek a secret card" action, so I suppose you can house-rule it as you see fit. The difference between your 2 examples is that the first one cannot be resolved regardless of the player's choices, while the second one could be found if you had made a different choice.
It will be possible to use these sign tokens in the future.