Indeed it was checking the Region set in Control Panel.
I think I found a better solution: In Registry Editor Under HKEY_CURRENT_USER/Control Panel/International
You have the date and time format of the machine.
For example if you want to get the ShortDate then you need an assign activity:
string shortDateFormat = Microsoft.Win32.Registry.CurrentUser.OpenSubKey(“Control Panel\International”).GetValue(“sShortDate”)
Others values you can use there are: sShortTime, sTimeFormat, sLongDate etc.