Woah, that sounds interesting...
I also think Holy Day would be a memorial day. A day to remember the horrible things that have happened, but also a new beginning, like AoYokai said.
Afterwards they could have some celebration days.
(I dunno if they can plant tree since it's between winter and spring. XD When do people plant trees? But it's a nice idea... ahh, and honey pastries, oh yes, Karan would love that idea...)
Yeah, they should thank Elyurias. XD Oh... we need to do this stuff for the rc blog... at least posting a lot of headcanons.