Skills and other parameters are stored in the .exe file, and even if you increase their maximum number within the .exe itself, it won't have any effect because the functionality is implemented by the developers not as an .xdb file, but as functions within the .exe.
Version 3.0 was successfully decompiled, or perhaps they used the source code (because without the source code, it’s very difficult to delve into someone else’s code, since reverse engineering is a time-consuming process; or maybe the person who figured out the functionality had a lot of time and, most importantly, was highly motivated) – the result is MMH5.5, however, this version cannot work with scripts added in 3.1!
P.S. I use Free Hex Editor Neo and HxD.
P.P.S. By the way, for version 3.1, the number of IDs for artifacts has been increased, and many new ones have been added - NAF

---------------------------------------------
Неудачное планирование ведёт к неудаче ...
NCF - мод, добавляющий дополнительных существ в HeroesV 3.1