Earlier quoted context omitted.
Maybe this? http://www.ames-fps.com/adoctrinamiento_libros_sociales_5y6p... Or maybe the many accusations of events like this one http://baluartedigital.opennemas.com/articulo/separatismo/vi...
The first link seems to be the most solid proof that unionist parties like Ciudadanos use to ask for investigating the Catalan school system for indoctrination (An investigation I think could be done, as long as there's enough guarantees that it will be impartial and not a witchhunt). It was made by a syndicate that seems to be pretty much nonexistent (see https://www.ara.cat/societat/denuncia-ladoctrinament-llibres.…
About the anecdote, a single case... there have been at least a couple dozen reported. Who knows how many were unreported. Even if they're kind of isolated, they show what kind of environment may exist in some places.
Personally I don't care, I don't have any stake on the matters. I don't like either side.