Based on my understanding of how your sticky nav works, the amount of elements you have is fine for several reasons.
- It already meets the speedy needs of most of your visitors.
After looking at Nielsen Norman Group's 5 Types of E-Commerce Shoppers, your site visitors are likely:
- Product Focused (going in already knowing what they want to purchase)
- Browsers (want to find new and interesting things)
- Researchers (collecting info about products)
Browsers (and Researchers) are already going to take their time. Product Focused will care about the speed to find the Take Course button and price. Researchers will care about all 4 elements, especially quick navigation to the reviews (assuming clicking the rating takes you to an expanded review list).
- More options complicates your mobile experience. (Sticky Menus Are Quicker To Navigate - Mobile Compatibility)
Have you considered what your site will look and function like on mobile? You may end up hiding your sticky nav or simplifying it to just show the Take Course button, price and Wish List button due to space.
I wouldn't worry about ratings. I couldn't find data on this at this time but people do read reviews, regardless if the rating is high or low (e.g. "This course looks interesting so why does it have a low rating?"). A user could dismiss a low or high rating if they find the review not applicable to themselves or their needs (e.g. A 1 Star review says "This course is way too short" but the user prefers a shorter course). Reviews are also a way to build trust with the Researchers and other visitor types.
I feel I should mention that my research continued pointing out sticky navs are great for navigation, not just simply keeping the "most important" buttons visible. While it isn't wrong to put call-to-actions, search bars or other interactive elements in them, consider if you're site could be better if that sticky nav could help navigate to different areas of the page, if applicable.
And when considering how your site will use your three nav bars, make sure they don't compete with each other. You may need to condense, remove or combine them.
For a competitive comparison, take a look at this course page from a competitor, Coursera, and their home page. They utilize sticky navigation as well.