Do languages have rights?
It's really simple: languages are tools. Languages do not feel, do not suffer, just like a key, a car or a computer.
Languages also have no territory. They are nowhere at home. Languages are not living creatures being persecuted and thereby needing protection.
Anyone who presents languages as living, suffering subjects, appeals preferably to younger people in order to evoke their compassion. Young people think in an idealistic way and fortunately have a tendency to protect the weakest. This idealized representation of languages is nothing but an attempt to brainwash.
If languages were part of a nation's wealth, let's imagine the US with a different language in each state. The Indian Constitution has 21 official languages. What do the Indians of different regions do if they want to communicate? They use English without ideology, the language of their former colonial master. How rich must Nigeria be with 514 languages? Which language do they use? Likewise the language of their former colonial master. Just as these nations use other tools, keys, cars, computers, etc.
These examples can be continued indefinitely, with French being, of course, the communication tool of choice in former French colonies. When in the Philippines the colonial power moved from Spain to the US, the official language changed from Spanish to English. (The Philippines have a second official language: Filipino based on Tagalong)
What about the rights of the speakers of a language? The speakers have rights. In Spain, this is consistently regulated in the various bilingual and multilingual areas by the fact that the regional languages are the official languages alongside Spanish. EU citizens do not have the right to use their language as an official language, e.g. English or German. A reasonable ruling, I think.
Reasonably, I also find that taxpayers' money is made available to the spokespersons of regional languages, to care for their languages, their culture, etc. That's what you do for Spanish as well - at least in the other areas.
We have a worse case scenario, the Separatists think they have to fight Spanish. They would deprive Spanish speaking parents of the right to choose the language in the education of their children in school. They think that they have to coerce the children to use the regional language to save their regional language and their regional culture.
Imagine what would happen with religion if at school, children were compulsorily taught only religion A, because religion A had to be protected, and because A belongs to the area and it stems from that area.
I think everyone who is interested in preserving their language, culture, religion, etc., must be allowed to promote it, then those who want, can join.
If, in view of the linguistic conflicts in Spain, you now believe that the separatists are more stupid with their language policies than the peoples of India, Nigeria, the USA, etc., you are mistaken. They are not stupid. They want to separate people with stubborn nationalism and prevent communication between the peoples of Spain. They are fanatics like the Priests of the Conquistadores in South America or the Inquisition that ended up burning heretics and books. Preventing communication is destructive. Granting rights to languages or tools is manipulative. We must not fall for it!