I just wanted to say wow on the recommendation for
https://fantasy-calendar.com It's extraordinary!
For what people have to pay for Realm Works I'd hope their development team would catch on to an obvious functional need requested several years ago.
Devs! Get on this! Even offer to the developers of that site a solid cash amount to port in the functionality and tie it to your timeline. Years, moon phases, calendar events, Then get the timeline function to let people pick custom years and setup eras.
There's a need for us world builders!