This interface uses buttons to allow the learner to display a text description for one feature of the illustration at a time. In this way, the illustration is never separated from the text that supports it. The illustration has been tested with subjects representative of the intended audience. Illustration design, like instruction in general, is not an exact science. Going through this or as many other checklists as you like still does not ensure that the illustration is going to teach your learners what you intend.
Any instruction needs to be evaluated before it can be assumed to be effective.
Find one or more subjects who are similar to your learners in their level of knowledge of and experience with the topic, and ask them to explain what the illustration is showing. Provide a list of questions that you would expect them to be able to answer after studying the illustration and the related material. Based on their responses, you should be able to diagnose problems with the illustration or determine possible improvements.