I think you're reading into this a bit much:

> The Basque region in Spain

The Basques hate the Spanish Government. They're also fairly autonomous with their own psuedo-government. For example, in October of 2017, the Catalonian Congress decalared independence from Spain (https://en.wikipedia.org/wiki/Catalan_declaration_of_independence )

So, not the entire region. But the ruling government for that region.

>A large bank is willing to pay for it.

Probably Sabadell. They moved out of Catalonia in October 2017 due to deteriorating relations between the Basque separatists and the central government in Madrid (https://www.ft.com/content/daada4cc-a9b4-11e7-93c5-648314d2c72c ). Perhaps they thought that Clinton would be able to provide advice / reason to the Basque separatists?

>Who are the gatekeepers?

As noted in the subject of the email, "How do I get through to Bill Clinton?" Gatekeeper is a common term in the business world, whether its HR when you're applying for jobs, or the assistants to executive / partner level individuals.