No need to use any mapping load.Use a straight table .add one more calculated dimension.in that use the aggr() function.In the expression just write any 1 and then hide the expression.You will find your desired answer.
the aggr() function will be like =aggr(max(orderdate),Region)
I don't see why do you need a long and complex script while you can have it short and simple.
Biren Agrawalla, As a rule, it is better to have actual fields rather than calculated dimensions - same result but better performance. Still your solution makes sense if the max date is not the absolute max date per Region but within current date selection. Even in this case, I'd rather move this expression from calculated dimension to expression. And, in expression, no need to aggr() because Region is a dimension already, simply: max(orderdate)
the aggr() approach is a fast solution to get results on the fly. However, as data volume increases, having a calculated dimension can become so heavy for your application, impacting in performance times. So if you have access to script is better to make as much pre-calculations as you can in script,