If it's just a question of what to call it? I agree with most of the people here. You do you.
If it's a question about tips on designing your cultivation system and how to develop it with your world building, my advice is to not just make it a part of your power system. Find a way to make it incorporate into your entire world building. In the system I created, it is energy of the spirit, also called "spirit energy." It has the property of reacting to thought and belief.
I have developed the energy that feeds the cultivators from a top-down approach, starting with heaven. The reason you can get anything you want in heaven is because heaven is literally made of spirit energy, which means a simple thought in that realm warps reality to make it conform to your thought.
Spirit energy is also the reason elves exist in my world, as well as fairies and other things. All the creatures designated as "fey" are a consequence of humans unwittingly creating them from spirit energy.
In short, the cultivation energy in my world is not just an excuse to make people stronger. It is a fundamental building block of the world, and has several consequences that reach far beyond the act of cultivation. I did not write a cultivation novel to write a cultivation novel. I decided to write a fantasy story, and as I was going through the world building and it was starting to shape up I decided that making it a cultivation world was what fit this world building the best.
That... is probably a bit of a different approach to a cultivation world story, and I will admit mine certainly does not feel at all like your typical cultivation world story, but I also think it is good advice to incorporate something like the energy that's used to make it do more things than just make characters stronger.