I personally do not pay too much attention to the scientific...

I personally do not pay too much attention to the scientific part. There are plenty examples in the world when scientific recognition came way too late after a discovery. For example like this one
A Hungarian physician working in Austria, Semmelweis noticed that one hospital of his had very high death rates. He theorised that this death toll could be lowered by surgeons washing their hands between patients. Semmelweis’s theory was correct. Greeted with such an easy way to reduce mortality, obviously, his fellow practitioners welcomed this research. Wrong! When Semmelweis talked about his findings to other medical practitioners, he was disregarded and accused of calling them dirty. After years of trying, he finally gave up and ended his days in an insane asylum. It wasn’t until around 20 years later that Louis Pasteur’s germ theory inclined more people to wash their hands often and, sadly too late for Semmelweis, he was proven right.
Scientists are very conservative by nature especially when new discoveries contradict their lifetime work.
Anyway, just typing "a2 protein peer reviewed research" into google search will give you plenty information you are looking for
https://nutritionj.biomedcentral.com/articles/10.1186/s12937-017-0275-0
https://www.agresearch.co.nz/news/a2-milk-study/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4818854/
https://www.researchgate.net/publication/334732932_Research_on_A1_and_A2_milk_A1_milk_is_not_a_matter_of_health_concern
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3475924/
and so on