i guess to my opinion, the date you give to Bank statement date in Bank account statement is not there for filtering rang of transactions. It’s AX out of box feature. Bank statement date will not filter the transactions inside and it will show all the transaction till date posted.
If you wish to have filter on Bank statement date then you need to get it customized as it’s given in AX like that only but there is another way is in Account reconciliation form on date filed you can right click and select Filter by field option and then you can enter date like let’s say for example you want to filter all the transactions before 12/31/2014 the you can simply apply filter as <1/1/2015 and enter. it will get you all the transactions for that period below 1/1/2015. or you can apply like 1/1/2014…12/31/2014.