They haven't that we have evidence of.
This isn't happening at a calm time in their history. They're barely staying in a very nasty war, their internal political factions are starting to experience significant friction, and now they're going to learn the council not only wasn't able to keep them safe but that it was actually the source of a major threat.
In canon just Peabody being revealed then dying was enough that the council almost splintered. Literally the only thing that saved it was filling an empty council seat with the leader of the splinter faction.
This is all of that, plus an monument to how profoundly incapable the council was at dealing with him.
There is no nation on earth that would deal with an equivalent loss calmly.
They are staying in this war by virtue of their people.
Of the Senior Council representing a strategic force in being that can be deployed, buying them time while they rebuild. By the Senior Council mobilizing allies and calling in old debts to buy time.
Fortresses do not win wars. People do.
And if you think the Council's members find the Halls more important than the most powerful wizards in the world, I dont know what to tell you.
The Council was at risk of splintering because LaFortier was murdered, and he was an advocate of wizards from African and Asian countries, who took offense. Georgio Cristos took the opportunity to use it to push for political power.
Whether Cristos is Black Council or just a power-hungry dupe remains unknown.
Peabody's exposure had nothing to do with that.
Man thats just not true.
Every extant major power has taken proportionately similar Ls and swallowed them instead of focusing on saving face.
Mab was literally attacked in her home less than a year ago, and was later forced to have her daughter killed .
Lara Raith canonically had a rogue archmage come into a Whampire meeting and murder most of the upper nobility of the White Court, then a couple years later, a naagloshii come into her home and kicked her and her sisters around and murdered half her security force.
Hell, the White Council literally lost >70% of its army less than 2 years ago.
In fact, the ability to take Ls and keep focus seems to be the difference between successful factions and dead ones.
It is their capital.
It's where they keep all their nuclear teir people. Where they run their military's high command. Where they host meetings of their entire citizenry to hold votes and set policy. Where they accept diplomatic envoys and perform various functions of state. It's where their operational records, most important library, and highest power artifacts are.
The white council doesn't have cities to lose, this is the equivalent value of DC and NORAD packed into one fortress.
The material loss is a huge problem, but the lethally serious one is the political aftermath. It's basically the equivalent of a person getting stabbed then going into shock until they bleed out.
Even if they just moved the senior council to another less impressive fortress it wouldn't change the fact that they'd have a smoking hole in the ground declaring them powerless and untrustworthy failures.
It is literally military doctrine that POTUS promptly evacuates the White House and gets put on a plane during international crisis, leaving the White House and Washington DC to burn.
People do not exist for capitals. Capitals exist for people.
The material loss is a huge problem, but the lethally serious one is the political aftermath. It's basically the equivalent of a person getting stabbed then going into shock until they bleed out.
Im going to quote it again:
Turn Coat c14 said:
The Hidden Halls of Edinburgh were the redoubt and fortress of the White Council of Wizardry from time immemorial. Well, actually, that last bit isn't true. It's been our headquarters for a little under five hundred years.
The White Council has existed since pre-Roman times, in one form or another, and its headquarters has shifted from time to time, and place to place. Alexandria, Carthage, Rome—we were in the Vatican in the early days of the Church, believe it or not—Constantinople and Madrid have all been home to the Council's leadership at one time or another—but since the end of the Middle Ages, they've been located in the tunnels and catacombs hewn from the unyielding stone of Scotland.
Edinburgh 's tunnel network is even more extensive than those beneath the city of Chicago, and infinitely more stable and sturdy. The main headquarters of the complex is located deep beneath the Auld Rock itself—Castle Edinburgh, where kings and queens, lords and ladies, have defied, besieged, betrayed and slaughtered one another since pre-Christian times.
There's a reason a fortress has been there for as long as mankind can remember—it is one of the world's largest convergences of ley lines. Ley lines are the natural currents of magical energy running through the world. They are the most powerful means of employing magic known to man—and the lines that intersect in the earth deep below the Auld Rock represent a staggering amount of raw power waiting to be tapped by someone skilled or foolish enough.
The Council has moved before. It will move again in the future.
Of course, this entire argument is irrelevant, and based on false premises.
The best place to save the Hidden Halls from is from the Senior Council chambers.
This fortress was built by the Fae, for a Fae lord. Ergo, any secret controls and overrides for the fortress, any secret defenses, will be in the Senior Council chambers, which are where the old leaders used to live.
If you want to save this place as quickly as possible, you want to get Ebenezar there as fast as possible, whether the Senior Council is entrapped in the Senior Council chambers or elsewhere in the complex.