This is the fix for the second problem in issue #86 (closed). The problem lied in the conversion of time metadata from numeric value to date if the unit is 'month'. The code didn't consider different types of the calendar before.
I ran the unit tests of the calendar issue and they worked fine. I don't have all the possible cases regarding the combination of different calendars and units(*), so I can't guarantee the calendar issue is completely solved.
We can either merge this fix now and wait for potential errors to happen (if there is any) in the future, or ask if Marga can provide us different data to do the test.
(*) calendar: gregorian/360_day/365_day
unit with or without 'since'