A really great photo, really well presented, and something that appeals......but.............
Not really Contre-Jour.......The main light source is really coming from the side, and not really taken 'against the light'...........I do not get the real feel of the effect here.......
In terms of composition, The lighthouse is a little too far to the right. it would work much better if it sat on the line of third instead.......I would have kept the room to the left, and just added space to the right, giving a more paroramic crop........the border does work well here, the lighting is good and the subject interesting.
Will still score this well cause its a great photo, but that it doesn't really meet the challenge IMHO is why this is not the top photo in this challenge. This in a free study (especially with the adjusted crop) for me would score very high.......