IIRC, his lawyer said CR came to this country with a 7th grade education, which implies he was educated in Mexico in Spanish. Of course, we've seen that he does understand conversational English, which would be expected after being here a few years.
He will need a translator in court to make sure he understands what is happening to him in the legal system. Otherwise the risk is an unfair trial, which would be a justifiable cause for appeal and possible overturn of any conviction.
I'm counting on translators at every single step of the process to make sure everything is doing correctly.
jmo