Thank you for your very thorough explanation.
I understand it very well!!
I have one last question: when I adjust the ID of a 5th generation Pokémon, I get a legal decision, but the IV of the actual individual that appears obtained by using the tool and the IV of the current individual are divergent.
For example, I changed the PID of my Kyurem from "E10061FA" to "38C24AAF" to make it shiny, and Kyurem's original status is "Hp273,Atk220,Def155,SpA209,SpD140,Spe153" but the tool shows The status displayed by the tool is "Hp285,Atk213,Def171,SpA198,SpD154,Spe167".
In this case, the IV of Kyurem is not changed and just adjusting the PID will result in a legal determination. Therefore, is there any discrepancy in the internal data of the Kyurem if I make the adjustment without considering the IV?