We've had a disagreement on how to determine what color card to score when Mannekin Pis A stage 2/3 copies Stonehenge B's stage 2.
Rulebook on Stonehenge:
Stage 2: At the end of the game, the player flips face-up the card used to build this Stage. Then, the player scores 1 victory point for each card of that color pre-sent in both neighboring cities
Rulebook on Mannekin Pis:
Stage 3: The player applies the effect of the last Stage of the Wonder board to their left.
Does the Mannekin Pis player use the color of their own tucked card, or the color of card the Stonehenge player tucked?
Our assumption was that it was Mannekin Pis' tucked card. After all, MP does not require the neighbor's stage to have been built, so the other interpretation could lead to a poorly-defined state where there is no card to reference. However, "applies the effect" was vague enough that we weren't completely sure.