Judge Joaquín Aguirre has identified a problem: many Senegalese etc can't speak their national language, French, to a level that would enable them to understand the information given to them. But his well-meaning solution - translating into Wolof or whatever - is actually worse: state education in for example Dakar is conducted in French, and the prayer schools flog the holy book in Arabic, so men who can read Wolof or other regional vernaculars are actually far harder to find than the 50% or whatever who are literate in French to primary-leaving standard. It would surely be far more intelligent to give more encouragement to the unofficial use of bilingual inmate-mentors to aid the illiterate.
With the South Asian languages he may have a point, but even there the broader question needs to be raised: these simple lads have reached adulthood without acquiring the skills which we expect here of 11-year-olds, so what on earth did they hope to do anyway in Spain, unless it was collect scrap metal from the streets?