I’m sorry for the misunderstanding. A guidance counselor wouldn’t need to know how the UCs calculate GPA to advise a student to build to take more rigorous courses instead of piling them at the beginning and then not continuing on that path. This applies to many schools, not just the UCs.
In your son’s case, he took 4 years of AP history so he received a bump in his UC GPA for APUSH and APWH.