A check-in in Facebook should be synced with Trakt
Problem: Have to redundantly check-in to Facebook and Trakt while watching a movies in theatres. Also Accessing Trakt through mobile is not so friendly
Solution: Connect the FB account to Trakt. Read status so that while someone is "Watching" something you can check-in the same movie into Trakt and Scrobble it
Not sure we can do this from Facebook to Trakt, but will look into this in the future.
We support checking in on Trakt, then syncing that to Facebook. No current plans to support the other way (not sure we even can easily). In addition to the website, there are lots of mobile apps that support checkins. Movist on iOS is one example I use myself when watching movies in the theater.