The confirmation of air victories of top Allied aces by LW sources?

[GuerraCivil]

One thing that has bothered me is the difference of air victories credited to top French ace Pierre Clostermann - in some sources he is credited with 33 air victories while some argue that he had only 15 confirmed air victories. Is the difference caused by the difference between total claims 33 figure including "shared" ones, probables and 15 are those of confirmed individual air victories credited by RAF?

When it comes to the French, I would be interested to know if the claims of Normandie-Niemen group are considered more "confirmed" or have been verified more precisely than the claims by regular Soviet IAP units?

Although there are some well-founded prejudices toward Soviet records, I´m not sure if they actually overclaimed much more than others (Luftwaffe, RAF, US) if one would have enough material to study very carefully the records of all sides and make a comparison between them. The reputation of Soviet records may have suffered from the ill-fated Winter War campaign when they claimed more enemy planes than the enemy actually had!

Perhaps it was not that much exaggerated during the whole WW2. As the whole combat stats of Luftwaffe vs. Soviet air forces is too much research work and too difficult, I wonder if there has been any case studies about individual Soviet fighter units and their claims compared to known Luftwaffe losses?

Maybe it was after all some Soviet ace who shot more Luftwaffe planes than any other Allied pilot? To my knowledge they did flew a lot like their Luftwaffe counterparts if they survived and there were not such rotations like in the Western Allied air forces. I´m not sure of Aleksandr Pokryshin´s record but the fact that he survived alive from the combat carnage against Luftwaffe´s air dominance during 1941-1942 tells something about him.