Hello Liesel,
I am not sure if anyone has translated the entire curriculum into Spanish. But you can find some LR files in Spanish you can download and import into Little Reader
http://forum.brillkids.com/downloads/?cat=64I do not think you will be confusing your son by exposing him to many different languages at the same time. You could designate specific days of the week to teach the different languages to make your daily schedule feasible. It's hard to fit in all the early learning lessons during the day so I usually make a list and some days we get through everything and others only some or none at all.
Your son is lucky to have parents who can expose him to so many languages. I am learning Spanish, Mandarin and Hindi as I am teaching him.
Surprisingly he does not mix the languages and when he speaks in one he will identify what language. But mixing the languages is natural and if it happens the child will grow out of it. Before each language lesson I make sure my son knows which language he will be learning about.
I look forward to hearing more about your early learning experiences