10% of Basque don't speak spanish but 100% of them studied english as a second language. Besides, I prefere to have as a reference the source language much more than another translated one. Therefore, I thing that matching a small language with his dominant language (spanish/french), it's not a good idea for the development of the small one. -Sator (talk) 23:23, 1 January 2017 (UTC)
Thanks, that's useful. You mean the 14,7 % for "Elebidun hartzaileak"? What does the term mean?
Now what makes you think that the people knowing English are more than 85 %?
Even if those numbers where made up numbers (I don't mean they are). I think is more likely for a Basque/French speaking user to be fluent in English than in Spanish, so I agree that Spanish should not be the fallback language.