So yes, what are actually the bottlenecks regarding the Great Library in your opinion? Why would these bottlenecks be better off resolved by holding off this boon?
Action costs in hypothetical "Belegar CK2 Quest". Considering it is Transcendent Boon, Belegar cannot refuse once we state a Boon, unless we explicitly ask him to postpone execution until feasible. At which point, might as well postpone it.
Diplomatic actions needed to gather the cool tomes are all busy figuring out new dwarf balance of power, and trying to gain some benefit from Imperial attention to the development. Oh, also the Dragon, not sure what's his status gonna be.
Martial actions...well, all busy, but they are not really needed for Library, so w/e.
Stewardship actions are constrained by commerce set-up and rebuilding pretty much all but, like, three Peaks.
- As a subset of this, engineers are 200% busy rebuilding Gate, fortifying Wyvern Caves and doing myriad other rebuilding things
Intrigue actions...well, we do not have those, and those, again, are likely all busy figuring out where what Ork tribe is or w/e.
Learning-wise, Mathilde is busy with other projects (this won't change, but still, we should carve out a bit of time for our part in Epic Project).
Gunnars is busy resanctifying stuff.
Kragg is busy opening vaults and grumbling at disrepair of everything.
In summary, actions - the most precious resource of Belegar's quest to rebuild K8P - are extremely constrained.
And what would people be wanting then?
Like i'm not opposed to waiting, i just don't want to uncertainty, make a decision, tell it to Belegar, provide a timetable on when to start and on what budget.
And we can bring in even more workers with just gold, Thorgrim has sent a throng but that does not mean other Karaks don't have people to hire.
If they will be wanting something else, it's a good thing we'll have waited until they thought up this another possibility, no?
Re: buy more workers: we were at worker and soldier shortage every day of Reconquest, far as I recall. All those heaps of gold...helped, but did not solve the issue.
Now, at peace (relative one) people will indeed float here more, sure. But there are now 8 peaks to deal with, not one, so amount of work is massively increased, short-term.
Now, once initial 3000 years of backlog of disrepair and looting are dealt with, Karak is indeed going to utilize manpower*, relative peace and space. But until that moment, state of....being permanent battle-/looting ground of Skaven and Greenskins, plus broken gates and proximity of Badlands, and other issues, will be a massive timesink.
* mind, manpower is still going to be an issue - we are likely going to all fit in comfortably in 1-2 Peaks out of 8. But once gates are fixed, Skaven tunnels are dealt with and other fires are put out, what people are there can be used for something less urgent.