Double-criminality is not an absolute requirement for the execution of an EAW. The most common categories of crime are explicitly excluded from such a requirement - precisely because the whole point of the EAW is to speed up extradition of the most common cases. It just happened that Spain attempted to prosecute Puigdemont for a crime that did not fall in any of those categories. That decision was mostly a sign that the Spanish government that initiated the process was not very competent on this subject.
