My main theory:
Lamentations is an Abyssal Exalt that used the Free Will of a mortal human to choose to not push for the annihilation of Creation. A power that's of the ocean of oblivion that the Neverborn are in, but isn't aligned against Creation existing. If there was only Oblivion there'd be no Hunger and no way to sate that Hunger. There'd be nothing at all. That wouldn't be bad but it's not the preference of the mortal of that Exaltation. If nothing exists and there's no past, then it doesn't matter when Creation is sunk to Oblivion which means it also doesn't matter if the Abyssal acts to sink Creation today because nothing will exist including the decision they could make so they're allowed to procrastinate since it won't matter in the end.
Rules Lawyering basically.
The Ocean, then, is the next layer down from where we're at. Where the Nephilim was at could support 2nd Age workings, so this could also be a place of 2nd Age (and the Ocean would be 1st Age) or this could be 1st Age and the Ocean is whatever the Primordials were cast to when mutilated into the Neverborn. The implication that things went off early could be the fact that the whole working was supposed to get all the way to the Neverborn but didn't make it before everything involved (but the Abyssal and the Nephilim) died. Stalling out in 2nd Age when you need to get past the 1st Age to find the Neverborn would be a failure for sure, but also just making the attempt would drag mortals (and apparently even Vampires) so far into Oblivion that they can't/don't survive.
maybe we can get the Abyssal to make choices that we'd like it to make. Maybe the best thing for it is the current state of things (mostly eradicated Black Court, mostly inactive Abyssal keeping an eye on the Ocean). There's an ongoing theme of our Infernal nature allowing for better outcomes than the perpetual stalemate suffering of Dresdenverse or WoD, so I won't say definitively that there's no way to recruit/help Lamentations in a way that'd be good for Creation/Us. That said: I'm for slow rolling this and doing our best not to fight