"make understanding difficult" is correct and usable in written English.
You can use it whenever you need to indicate that something is hard to understand. For example: "His obtuse language and convoluted arguments make understanding difficult."
As she increased her background knowledge of China, she realised the gap between educational schema that made understanding difficult for her students.
Also, I found the paper to be lacking a surprising number of essential experimental details, which marred the presentation and made understanding difficult.
However, complicated reactions, as well as heat and mass transfer, make understanding the process difficult.
Obviously, using a portable radio should be used with an earphone - which can make understanding transmissions even more difficult.
The absence of either internal angular calibration for most of them, or intercomparisons prior to the operational phase either from ground or space, make understanding the origin of the discrepancies difficult.
The question is not so much what Lay understood; it's why the board allowed for structures that made understanding so difficult.
Collaborative problem solving often involves actors with heterogeneous competences or that see a common problem from different perspectives: this can make mutual understanding difficult.
It comprises several muscle parts that are often difficult to discern and which have, over the years, been given several names, making understanding even more difficult.
Studies in these areas are limited, which makes understanding these mechanisms difficult.
For example, I will ask if the store has such and such an item, and the reply is usually quite rapid and long, which makes understanding it very difficult.
The paper is written in a way which makes understanding it very difficult.
