Hey,

need some help here :) - the hint doesnt help as i cannot destroy (or expose) a core
I think the building around it is meant to be "indestructible" and something is "inside" to destroy (tried many things up to nukes - which destroy the building but only gives "normal" lava and and artillery which doesnt do a "dent"

is it tied to the alarm rating for them to expose themselves (because that needs me to expand much farther and that with limited power :) ) or is it something entirely different?

It sounds like your nukes create normal vulcanus lava when shot? Maybe another mod is interfering here. Any idea which one it might be?
You were on the right track, but I think if you replace the floor below the vault with lava it will just despawn instead of being destroyed. Maybe it needs to be more dentable.
Just to make sure, you have not gotten any core to spawn, right?

Nope, just the normal building that spawn the robots and have the military loot leftovers around which can/must be hacked to get specific ressources.
The nuke did destroyed it .. but only left vulcanus like lava and no alarm response either

So it sounds like i need to get a core to spawn but that i am not aware how to accomplish.

Okay Update:
Ran the game again with only your mod .. cheated myself to Rabbasca and used a nuke again ... something different is happening.
so it might be a mod issue but i dont know which one.