What do you find hard to reason about when it comes to Redux? There is some terminology, but the heart of Redux is a pure function that takes a state, new information, and returns a new state. That's hardly rocket science.
You are definitely not the only one who has not found Redux "easy to reason about". I think the concepts are somewhat straightforward, but in practice are a little harder to grasp, especially in real world applications.
This buzz phrase "easy to reason about" is so popular in the React world. I feel like I'm the only one who finds it oxymoronic. Especially with regard to Redux, which I think is anything but.
Angular 1/2, Ember, Backbone are all pretty "easy to reason about", so much so that it is rarely pointed out.