So, what are you trying to say ?
The course should only be using words that you know ?
So, please tell us....which words do you know ?
Do you have a list of those words somewhere online ?
Or....The course should only be using words that everybody knows ?
What are those words ?
Which words should be excluded ?
Wow...I'm wondering what kind of a course that would be.
but because anyone speaking English who isn't Buddhist, doesn't know that word.
That's quite a claim.
Something to back it up ?
You do know that there is something that's called a dictionary right ?
If you don't know a word, you can look it up.
That's a good way to increase your vocabulary.
And if are confused about why your dictionary comment isn't pertinent, please refer to this article: https://englishlive.ef.com/blog/language-lab/many-words-english-language/