My brain injury was much later, but also frontal lobe. I was 17. I had and still have the symptoms that you described, but they were more intense in the months immedietly after.
I still suffer from not having full control of my emotions and impulsiveness. Concentration can be trained and learned I believe, and in my non professional opinion I suggest that you start early with your kids. Get them to read more, introduce better planning skills so that they adapt to any problems they may have later in life when things are more demanding.

Thank you for this post. I wish I had seen it earlier -- somehow I missed all the posts after June last year. We started having our daughter see a behavior therapist, and I've also been doing a lot of reading on how to help children develop executive function skills. I'm hoping that maybe, if we work on these things now, it will help her as she gets older.