Actually that API is just for getting the date separator. As for the date and time format the program just calls the built in VB command of Date and Time. So it should be returned as the system tells it.
However! If you have the auto backup set to run as the system account, then I bet that the system account has different regional settings and thus we get the different folder names.
So try this, remove the auto backup and have the program do it under the current user account instead and see if that does the trick
Otherwise if you need it to run from the system account, then one trick you can do is use my technicians toolbox program and use the run as system account tool and load explorer.exe as the system account. Then you should be able to the control panel and change the regional settings for it
Shane