If the text in your copy of Stronghold Crusader 2 appears like the image below then the language files are missing. 

To resolve the problem please verify the integrity of you games cache and restart steam. 

This action will check that your game has all the required files for it to run smoothly. If any files are missing they will be downloaded automatically over Steam. 

You can do this by doing the following:

1. Load Steam.
2. From the Library section, right-click on the game and select Properties from the menu.
3. Select the Local files tab and click the Verify integrity of game cache... button.
4. Steam will verify the game's files - this process may take several minutes.

The full instructions on verifying your game cache can be found here.