Hello Laurelix,
Shortround6 already gave a pretty good explanation assuming that different aircraft designs are equipped with the "same" engine, but the problem here is that your basic data is incorrect. (....and also that the engines are not really the same.)
The Me 109E was equipped with two different engines. The DB 601A-1 was the standard. The DB 601Aa was the "substitute standard" with a smaller and less capable supercharger. Only the Aa version was approved for export. When the Germans in their benevolence licensed the DB 601 to the Japanese and Italians, they only licensed the DB 601Aa.
IIRC, the critical altitude for the DB 601A-1 was 4500 Meters and the critical altitude for the DB 601Aa was 3500 Meters.
Though the DB 601Aa was originally intended for export, significant numbers ended up in production Me 109E.
Two Japanese companies, Aichi and Kawasaki tried to build licensed "copies", but Kawasaki also tried to improve the supercharger a bit and managed to bring the critical altitude of their Ha-40 to 4300 Meters. Not quite as good as the DB 601A-1, but close.
I believe the Italians also tried to do something pretty similar, but I know much less about their attempts. The intended critical altitudes of their engines can be determined by the model numbers though I don't know if they actually achieved the intended performance. From performance statistics in books about Macchi fighters, it seems like they really did not.
- Ivan.