We've had several reports of awards not syncing with Google Play Games and the programer is a looking into this bug.
The Pocket Trains awards will not begin syncing until you are logged into to Google Games from the app. To login, go the the Pocket Trains menu and into the Awards screen. Tap on the icon of a game controller shown in the upper right hand corner and login to your Google account.
Anything you earn going forward should sync up right away and the previously earned awards will show up as they are triggered again. For example, opening a new railroad should trigger those related to operating a number of railroads, completing an event should trigger those relating to events etc.