quarantine 'em

For example, documentation seemingly goes to inordinate lengths to conceal the fact that this lunar calendar ignores leap days

Much is made of the lunar calendar's fine attempt to approximate 365.2425-day Gregorian years. It doesn't do this! It uses 365-day years

Just subtracting all the leap days out of the Gregorian calendar makes converting to the lunar calendar unimaginably simpler

Then there are epacts. Epacts require big, horrible, impermanent tables both to compute and to interpret. They are also absolutely unneeded

The epact of any given year is the "age of the moon [i.e. day of the lunar month] on 1 January". But sometimes it's 30 when it should be 29

The epact goes up by 11 every year, mod 30. But not always! It also doesn't tell you WHICH lunar month it is

Basically the epact is a highly complex derived property from a relatively simpler underlying lunar calendar

And understanding epacts just makes the underlying structure of the Metonic cycle seem unapproachable