This need to be thought upon further. The feedback could be implemented in various ways (they do not exclude each other):
Have the background music grow in epicness as more and more features become correct. This is also good for climatic reasons, but is in itself rather subtle.
Have the game over screen display a sort of "score" that give an indication of how many features were correct by talking about how much the Prophecy has been fulfilled.
Have the Dragon tell you that a feature is correct at the beginning of the round. It has the potential drawback of being too spoiling and confusing the polarity of other hints. On the other hand, especially if implemented with a depiction of the polarity of the Dragon's reaction, would be very clear and potentially would open up the design space for more difficult hints for some features.
This need to be thought upon further. The feedback could be implemented in various ways (they do not exclude each other):