In my experience in my area, schools do not try very hard at all to assist the reasonable parent who is not the residential parent (RP) to become the residential parent.
Of course they don't see that as their job (though it would be better for the child if they helped more in many cases).
They probably see their job as first covering their own behinds - avoiding lawsuits - and second, avoiding getting sucked into drama, and third educating all the kids. That doesn't leave much room for helping a parent in a custody case, even a parent they wish well.
There is always the option to subpoena a teacher or someone else from the school. I didn't do that, but I was counseled to call anyone I thought might be good to have testify, and tell them they would be subpoenaed, so they wouldn't be blind-sided. I would have made those calls just a few days before the trial, but we didn't go to trial so I never did.