Part of the reason this situation is so misunderstood in Ireland is people filling in the gaps in their knowledge of the country and the region with analogies based on what happened here. The situations bear little comparison.
Catalunya and its language was undoubtedly oppressed under Franco (as were other regions of Spain along with anybody else less than engrossed with his conservative Nationalism). That oppression ended when the 1978 constitution gave them a large degree of autonomy and cultural/language rights. Frankly, the seeds of this current situation were sown in allowing Catalunya unchecked powers in education, media and language policy in the region. It has allowed a lunatic fringe to present a lopsided and jaundiced perspective of the last century. Forty years ago, Catalans despised Franco for the decades of cultural suppression he imposed on them. Many of those that have grown up in the region since then have been brought up to despise Spain.
The freedom Catalan separatists seek is the freedom to ensure policies they’ve already succeeded in applying to some degree are imposed on everybody living in the region, whether they like them or not. For example, only 2% of Catalans don’t speak Spanish and they’re mostly elderly people in isolated areas, while 45% of the population speak little or no Catalan. Yet the Regional Government has succeeded in making proficient Catalan a requirement for almost all public jobs. That has largely limited employment in such posts to the native population in a region that has always had a lot of migration from other parts of Spain and immigration from Latin America. They obviously arrive speaking Spanish, a language 98% of the population speak. The obvious solution is the bilingual one the region had until relatively recently but that wasn’t enough for the fanatics, who ludicrously claim their language will die out in a bilingual environment. Don’t doubt for a second that there’s a large dose of calculated racism wrapped up in this policy.