Edit 2: As of 12/11, my comment below no longer stands, and this quest appears to properly award rep again.
Much to my disappointment, I picked this up today after weekly reset and the rewards were rather lackluster compared to I think every week I've seen so far...115 Kej and 225 Resonance Crystals offered. No choice of a 1500 Rep token. It also says the quest has been completed by my Warband -- which I am sure is true, but not this week.
I can't say for sure, but I'm inclined to think that all of these quests that Biergeth hands out are one time things. So, not a consistent source of an extra 1500 rep per week. And I guess we're at the point where the quests are starting to repeat? See my Edit below
Either that, or simply bugged. I'm hoping for bugged. These weeklies are worth nothing without the rep.
EDIT:: While this never got fixed during the week of 10/15, the new weekly on 10/22/2024 for Stonevault, which I am also sure I have done on a previous week, seems to be giving rep again. Maybe this Darkflame Cleft one is or was bugged. If this quest comes up again a few weeks down the road and it is still not giving rep, report it! I don't think it is intentional.