Just a minor bug I found that may have already been discovered. By itself it is not important enough to bother fixing but if there are other locations it might be worth looking into.
I was doing the event chain in Calx’s Hideout in the far Southeast corner of Metrica Province. When it came time to kill the 3 Veteran Golems, each one of them gave me credit towards the Guard Slayer achievement in the WvW Season 1 category.