Hi Jiwa, you can change the language by include the localisation file, You may find other localisation files here: https://github.com/jquery/jquery-ui/tree/master/ui/i18n

Ex: 

<script src="https://jquery-ui.googlecode.com/svn-history/r3982/trunk/ui/i18n/jquery.ui.datepicker-nl.js"></script>

 Fi the code of datepicker jquery ui in file script.js.

Ex:

$.datepicker.setDefaults( $.datepicker.regional[ "nl" ] );
$('#date').datepicker({
            numberOfMonths: 2,
            showButtonPanel: true,
            dateFormat : 'dd/mm/yy'
        });

 dateFormat: date format in datepicker. you may refer to page http://api.jqueryui.com/datepicker/. Thanks

Hi there.

1. Format Date: You can find function DatePicker replace with the code: 

function DatePicker() {
        $.datepicker.setDefaults( $.datepicker.regional[ "ru" ] );


        $( ".awe-calendar:not(.from, .to)" ).datepicker({
            prevText: '<i class="hillter-icon-left-arrow"></i>',
            nextText: '<i class="hillter-icon-right-arrow"></i>',
            buttonImageOnly: false
        });

        /* Datepicker from - to */
        $( ".awe-calendar.from" ).datepicker({
            prevText: '<i class="hillter-icon-left-arrow"></i>',
            nextText: '<i class="hillter-icon-right-arrow"></i>',
            dateFormat : 'dd/mm/yy',
            buttonImageOnly: false,
            minDate:0,
            onClose: function( selectedDate ) {
                var newDate = new Date(selectedDate),
                    tomorrow =  new Date(newDate.getTime() + 24 * 60 * 60 * 1000),
                    nextDate = (tomorrow.getMonth()+1)+'/'+tomorrow.getDate()+'/'+tomorrow.getFullYear();            
                $( ".awe-calendar.to" ).datepicker("option","minDate",nextDate).focus();
            }
        });
        $( ".awe-calendar.to" ).datepicker({
            prevText: '<i class="hillter-icon-left-arrow"></i>',
            nextText: '<i class="hillter-icon-right-arrow"></i>',
            dateFormat : 'dd/mm/yy',
            buttonImageOnly: false,
            minDate:0,
            onClose: function( selectedDate ) {
                //$(".awe-calendar.from").datepicker( "option", "maxDate", selectedDate );
            }
        });
    }

2. RU translation: i sent to you file datepicker-ru.js, you  can be saved to folder lib in hillter\js\lib and add link The bottom of the html file. Thanks 

<script type="text/javascript" src="js/lib/datepicker-ru.js"></script>

Hi there. Link download 

https://github.com/jquery/jquery-ui/blob/master/ui/i18n/datepicker-ru.js