Matalas himself says Frontier Day is the anniversary of Broken Bow: https://trekmovie.com/2023/02/18/ex...prise-roots-of-mtalas-prime-and-frontier-day/So, now it's 250 years since the launch of the NX-01?
Is that where everything is pointing towards what Frontier Day is celebrating?
Considering the whole incident is an embarrassing one for the Klingons anyway (Archer: I'll take that as a thank you/Sato: Klingons don't have a word for thank you/Archer: What'd he say?/Sato: You don't want to know), I wonder if we'll see Worf celebrating.

Shaw must've put Seven through some real hell if she's already wanting out of Starfleet after literally only 3 months under him, considering the weekly horrors she encountered for years on Voyager (including a literal episode entitled 'Year of Hell').