I want to also say I really agree with JustHappy that I would also "compartmentalize into 2 things - the academic side including to some extent not paying attention (which I'd give low priority) and the behaviour side (which is the most important)."
I also wonder if the mention of " Bright but not working to full potential which both us and teacher see." might potentially reveal that you and the teacher (and your partner) are all thinking that this child can reach potentials in the short term that a non-adopted child can due to being bright. I'll unpack that a bit...
I do think that adopted children in the long term can reach their full potential both in terms of academic ability and just as people generally, going on to parent brilliantly, live their lives full of good things etc.
But in the short term (as in, within a few years of being removed from their birth family, placed in foster care, potentially continuing to see birth family, potentially living with more than one foster carer/fostering family, being placed in a new forever family by adoption) I think it could be very hard indeed for any child to reach their full academic potential, no matter how bright they are. So I worry a tiny bit that either the teacher does not realise the full potential of what has happened to this child (not the specific details but the degree to which the child may be finding things difficult), or you may not (sorry I don't mean that rudely just that if the child has appeared to settle in well, or was adopted very young people can sometimes feel that all is well), or both.
Our son is academically OK but he is emotionally quite difficult, prone to upset, crying etc. It has taken some sessions of theraplay for me to really realize he cannot help the way he is acting, he is just coping. His early experiences have affected the way his brain develops and I really hope and pray that in the long run he will be able to handle emotions 'normally', and not get so upset, but in the short term (two and a half years in) he simply cannot.
His academic abilities are a super plus but I know that school for him is a mixed place, a place of fun and joy, but a challenge.
I knew all this in my head, having had lots and lots of excellent prep classes and post adoption support into attachment and post adoption parenting classes. BUT it really has taken a long time for it to sink in and to realise that he cannot always control how he acts and that punishments and incentives do not work the same way they work with regular kids. Even having a quirky daughter with autistic tendancies did not really prepare me for this and although it is hard it is, I feel, best to be honest about what my son is capable of at this moment in time. It does not mean he won't go on to great things but at the moment his early expereinces still massively affect him, even if most people look at him and just see a very cute little boy who clearly fits well into our family, and who is very much loved.
I hope that makes sense and doesn't sound rude. And if you are more than two and a half years in I am not trying to tell you how to suck eggs, because a few months ago, before theraplay, I would have felt quite differently and not been able to see fully how much my son is still affected by his early experiences. And that is in-spite of being on these boards for about 5 years plus and having this message drummed into me by a lot of people!
It does not mean we need to 'just accept' the diffiuclt behaviour but I think it does mean we need to be more creative and guided by experts (not teachers) in how to handle it.