I forgot that CalcNote supports the custom format.
You can enter the day of week using 'E'.
[計算設定]-[日期格式]-[自訂格式]
Enter 'yyyy年MM月dd日 (E)'. This example is a common date format for Japan. 'yyyy' is the year, 'MM' is the month, 'dd' is a date, 'E' is the day of week. Please note these are case-sensitive.