Are custom calendars possible yet?

[kbs666]

You really want to know about my calendar system?
There's the solar calendar most people use.
12 30 day months with a 5 day new year holiday.

There are 3 lunar calendars (3 moons) important to spell casters
Not alignment based but oriented towards spontaneous versus memorized casters with the third moon governing hybrid casters. This is sort of based off Dragonlance but only sort of, the moons all have their own orbital period.

The elves, dwarves, dragons and multiple human cultures each have their own calendars which all matter to the back story of the campaign as well.

I think at last count my spreadsheet for my campaigns calendar system had 15 different dating systems and 9 different calendars.