Not being familiar with the Bulgarian language, is it one where one reads from left-to-right (ltr) or right-to-left (rtl) that would determine whether the dir= tag would need to be modified away from its current left-to-right.

Having $reverse = true would provide a raw date in the order desired if the date is provided as mm/dd/yyyy. This is opposite of the "default". My suggestion would be to add a line after the function declaration and before the if statement that is:

$reverse = !$reverse;

That will/should take a false result and make it true or a true result and make it false. Should also verify that there is not already a function of zen_date_raw in the code because if so changes here would have no effect.

But also not sure if you are indicating whether the date is entered by the user in the series/sequence provided or if the result of zen_date_raw is as you have asked. I mean it appears that existing code may not work properly if the dat is provided as described in the code and the above modification is made because for example the account_edit page expects the first four characters to refer to the year when zen_date_raw has a false value for $reverse.

Now if the dates are provided as ddmmyyyy, then for "normal" output well... should just ask:

What date needs to be formatted as ddmmyyyy? The input or the output of the function?