When I did it for the shockwave jump achieve, I got credit for four in one fight. So it's not necessarily just one. My complaint is the alchemist is bugged up and needs to be fixed. Beyond that, I'm overall pleased with how it's ending. Farm the champs for events, little bonus whatsit achieves, get some keys, at least the chest is now giving some half-decent loot in return and you don't have to run the Tower of Failmares over and over to get to it. Yeah, the meta award is kinda blah, but did we really need another one-time helmet skin? A title might've been nice, but again, not necessary.
As for the Wintersday stuff, LA looks gorgeous all decorated up. Haven't done the group-required stuff related to it or the JP, doubt I will, but following the dolyaks while they poop gifts and booting skritt around was amusing for the related achieves.