Even though many of the citadels in the list were built in the spanish empire, Spain itself has no citadels in the world heritage list. I guess this fact doesn't sit right in the ministry of foreign affairs ,which is how we got yet another fortification proposal. The tentative site centres around a set of fortifications in the french and portuguese border. The best ones are the ones in figueras, jaca, pamplona and ciudad Rodrigo. Now I'll cut to the chase. I don't think the fortifications in Pamplona, the only ones I have visited, have OUV. Afaik they weren't particularly innovative at the time and significant portions have been torn down. They still make for a pleasant park and if you're in pamplona you should visit. However I don't feel like they add anything explicitay new to the list. Imo the strongest candidates are ciudad Rodrigo, which is hilarously included under "Romanesque Cultural Enclave in the North of Castile-Leon and the South of Cantabria" despite not being in the north of castille nor the south of cantabria, and San fernando in Figueras, which was built after the treaty of the pyrinees when Spain lost the valuable Fort bellegarde. These two sites might just be enough to wrap a proposal around so I will abstain from giving a thumbs down to the proposal, yet.
I actually think Ciudad rodrigo might eventually make it into the list. Though most likely not in a serial proposal but rather on its own, afterall it has a good acceptance rate in the community. As for figueras, I don't think the site has enough to carry a proposal. Though there's an interesting connection which could be exploited. its architect studied in the school of brussels which did play a fundamental role in the history of military technology.