First things first: You need an inside man high "enough" in their command-chain to even be able to plan something like this precisely enough. This inside man most probably has no access to this library.

So:

Their response-time is the most urgent question in assumptions about a plan like this. Because you need a lot of time to decide what has value and what has not, if you ever even could get into their library that contains this knowledge, even if you can find someone that has the necessary skills to make sound judgements on this. The tools to copy these books possibly could be optimized a lot and the weight you can carry is limited by your escape routes at least. Their containment on the inside of these buildings will be very solid, i suppose. This implies you need to bring tools to punch through barriers stronger than you initially even could expect in case you can't hack them.

Also: You need more than four sound escape routes, if you don't want to create a situation they regard as a "hostage-scenario" which implies the probable loss of more souls on both sides of this endeavor. Because in this scenario they will change their tactics, obviously. But on the other hand: Military tactics are quite standardized which you of course could use to achieve this goal.

It could be a real big win for all of humanity, so it could be an achievement worth the necessary sacrifices, for sure, i suppose.

And of course: A "big sound long enough" diversion, possibly even two to constrain and divide their forces enough to delay their coercive encirclement of this location.