Language selection not showing on Pages
Can you check your exact version of Sitefinity? To do so, go to your project's bin folder and locate the Telerik.Sitefinity.dll. Right-click it, choose Properties and then select the Details tab. You can see the version in the File version field.
Additionally, try to restart the application by making a dummy change and saving your project's web.config file.
I checked and see its "Small Business edition" so there is no bug.
Unfortunately 'multi-lingual' is not available for the Small Business Edition, if you'd like that option you'll have to upgrade to the standard edition.
The reason you're allowed to add a different language through the settings is because you're allowed to switch, but you won't have the ability to use both at the same time.