well, the wealth being redistributed is the "trigger" for the current move, but the Catalans always see themselves separate from the Castilians
Spain has a number of distinct regions -- like the Gaelic origin people of Galicia with a language that is more similar to Portuguese than Castilian, to the dominant Castilian (that we call Spanish)
and then of course there are the Basques whose language is a language isolate -- with some conjecturing that it is related to Georgian but no proof for that
The Asturians and Galicians are Celtic peoples, but their Celtic languages are long lost (the modern Asturiano and Gallego languages are Romance languages, more similar to Portuguese than to Castillian Spanish as you mentioned. Asturia was the one Spanish region that was never conquered by the Moors, and only a small part of Galicia became part of the Moorish Kingdom; the Reconquista spread out from Asturia and Asturian surnames (with patronyms ending in “ez”) became the most common throughout Spain as the Moors were kicked out.
As for the Basques, if scientists discover that they emigrated to northern Iberia from another solar system, it wouldn’t surprise anyone.