Library collaboration does not appear to be a leading feature of either group.
The IDEA League is a group of four leading European universities specializing in science and technology. Again, the website does not feature library interactions. (The name is an anagram of the first letter in each institution's name, a practice which if maintained rather limits growth opportunities ;-)
The individual libraries are of course meshed in a variety of other collaborative structures, and operate within national regulatory and legal structures. I wonder are incentives to collaborate lacking within these international alliances, or whether this is an area which will in fact grow over time, especially, maybe, as digital infrastructures become more important. They do provide an opportunity to diversify thinking about the way forward, as discussions can step outside local or national contexts.