Should I follow the curriculum in a different order?
you are not expected to know those methods, the description says that the rest parameter is useful when using them, and that’s true, but you don’t need to know them. The only thing you need to know is that they are array methods, but that can also be deduced from challenge description.
The change you need to do in this challenge doesn’t have to do with he methods.
If you still want to learn about them, just google about them. You will anyway be tasked to use them later in the curriculum.