I don’t have children or teach children, so I don’t know what to advise. This is more a question, why wouldn’t 12 y/o children use an adult Bible?
I can only imagine the tens of thousands of decisions that would have to be made to decide what a 12 y/o could or could not comprehend.
I was reading an adult Bible when I was 12 years old, I was a B+ student.
Even now as an adult, I am at the mercy of translators who have a difficult job carrying over the meaning of the text. Those who know Biblical languages often criticize the translation as not being exact.
Again, I can offer no advise nor should I, but here’s just a comment: Maybe the focus should be on WHAT they read, essentials that they should internalize, rather than trying to use somebody else’s opinion about what the Bible says. I would be afraid of they’re remembering the wrong thing about what the Bible actually says. That might create confusion and resentment later on, about their having not been told the right thing.
Perhaps the question here is, is there a suitable book of “Bible stories” for them to become acquainted with, with perhaps quotations of “adult” level text for them to focus on.
sorry if this is irrelevant to your needs.