I think I know why people get so sensitive about this. Hartmann has this amazing aura because of his 352 kills, and to put it simply, he sounds really cool. People like believing the idea of his 352 kills, and if you count damaged aircraft then sure it's 352, but if we only count destroyed aircraft, then he has at the very most 180-190. People don't like this fact because it ruins the image they have in their head about his 352 kills, which is crazy because 180-190 destroyed aircraft is really good. People seem to think that saying Hartmann has overclaims means you're being disrespectful to him, which is absolutely wrong. Everybody who investigates Hartmann's claims says he's a skilled pilot who had a good hit accuracy but just didn't finish off his victims.
Verified Victories has many different primary sources and the book is incredibly detailed. If you want the full analysis of German Aces over Hungary from 1944-45, then it's perfect.