Kids like when things are organized (although they can sometimes create chaos). Here's the first way you can keep their book selections organized by language.
Phonological awareness, the ability to identify and repeat rhymes, can be taught at home with lots of song and rhyme books in your language.
Why should I re-read the same books? Re-reading exposes your child to the same words over and over again. It gives them time to hear the word, understand it, and eventually use it.
Using words and illustrations in books, teach some of that missing vocabulary in an enjoyable, shared experience. No more forced speaking or disparaging. Subtle teaching, reviewing in context, and careful encouragements.