looloo I do that too, I get books in english and read them in spanish to ds, (4y/o)
I ask him if he would like me to read in eng or span and sometimes I tell him, its in eng should I read it in eng?
99% of times he likes me to read it in span and dh to do it in eng.
When the book is in span, its always read in span, dh wont usually translate them because ds wont ask him to do so.
Ive wondered about this one too.
Id love to hear more opinions about this!