Anthony B. answered 04/06/21
3.6 GPA Junior student studying for Game Art Design Bachelor's degree
Autodesk Maya uses a programing language called MEL (Maya Embedded Language) and is much like Python to run scripts. BUT...
Like you stated, Maya is developed using multiple different programming languages.
I suspect the reason is that each programming language has its advantages and disadvantages.
To boil it down to simplicity:
Python is very good at handling chunks of Data. It is much lighter weight than C++ or C# and is much easier to iterate with due to its dynamic nature and light type.
C++ is great for creating all sorts of programs. It is much more lightweight than C# and is compiled at the machine level. This allows it to directly interact with the hardware of the machine.
C# is the heavyweight of the three, is compiled virtually thus cannot run standalone, It relies on other software. It's a high-level code that is used in many modern development apps.
Maya is one of the most complicated programs I've ever used and I assume by using all three languages the developers can rely on the strengths of all three languages.