Here’s a good article summarizing why it sucks to be a student from a Spanish speaking family in Catalonia. Not only are the parents isolated from being involved in the school (100% of communications are in Catalan), but children are even being given bad grades for speaking Spanish on the playground. Adjusting for socio-economic status, kids from Spanish speaking family do significantly worse in school than their Catalan speaking peers.
Even for kids from Catalan families, their level of Spanish is so pathetically bad that they are basically unemployable anywhere else in Spain. Don’t even get me started on “oh but they learn Spanish from watching TV”.