WinRT: Regional Settings Misbehave?

Note: This is a repost of my Stack Overflow question. Feel free to comment here or on the SO.

I'm having some problems in Windows 8 Metro apps (XAML & C#) regarding the user's regional settings. It seems that the apps won't respect user's regional settings, so even if your Windows 8 is set to display dates and times in Finnish format, the apps will still display them using US-formatting. But this is such a big problem that there must be something I'm missing?

To test this I started by creating a WPF-application. The application just prints out the CurrentCulture and the formatted DateTime.Now:

private void Culture_Loaded_1(object sender, RoutedEventArgs e) 
        { 
            this.Culture.Text = System.Globalization.CultureInfo.CurrentCulture.DisplayName; 
        }

        private void Date_Loaded_1(object sender, RoutedEventArgs e) 
        { 
            this.Date.Text = DateTime.Now.ToString(); 
        }

Here's my default regional settings:

When run, the app displayed the date in Finnish format:

Then I changed the regional settings to US:

And when the app was run again, the culture and formatting changed:

This is as I expected everything to work and this is also how I expected WinRT apps to work.

So as a next step, I created a WinRT (XAML & C#) app with the same code and reverted the regional settings back to Finnish. The problem: 

Even when I've defined through regional settings that the formatting should be "Finnish", the WinRT app displays the datetime with US-formatting. I then modified the app's project file and made fi-FI the default language:

This change also modified the app's culture: 

Strange. I changed the Default Language back to its default value and the formatting was restored to US. I then created folders "Strings - fi-FI" inside the project and added an empty "Resources.resw" to the project. This empty file seems to be enough, as I was now getting the Finnish formatting: 

As soon as I remove the empty resource file, the formattings reverts back to US: 

Very strange.

Any ideas? Is this a bug, or something that needs to be considered when building WinRT apps? Any ideas how thing work on the JavaScript side of things? Please chime by leaving a comment here or on the Stack Overflow.