The rules say the Dwarf doubles the imprint gold when the board is scored.

Does it also doubles it when you play the "Score a room" card? 'Cause if you follow the rules by the letter, it doesn't.

Any official ruling on that?

We've been playing that he does. I guess that's not official, but I think you and whomever you play with can decide what you think is fair.

Scoring the board could be interpreted to mean any scoring on the board. To my knowledge, the places in the rules where you score the "whole" board say "score the entire board"; thus, scoring a room is scoring a board, or at least a portion of it.