I agree with Andreas that this is probably easiest to do with Xpath. Also fastest. You can also try with the special Xpath functions MonthFromDate and YearFromDate
https://docs.mendix.com/refguide/xpath-month-from-datetime
e.g. to get all data for december
//Logging.Log[month-from-dateTime(DateAttribute) = 12]
Easier than using filter might be to only retrieve the needed objects from database. If you only want to see objects from a specific month, you can create two date variables, a start date and an end date. In your xpath you can now only retrieve objects where the timestamp is greater than your startdate and smaller than your end date.