No, "junior" just means not as tenured, which is why it's used without any kind of negative connotation in job titles, like "junior project manager." You wouldn't use "junior" to as a negative commentary.
On the other hand, "juvenile" is a negative assessment of someone's behavior. Our junior project managers may act juvenile, but hopefully not.
Rather embarrassed at how many times I tried "jump" just to make sure that wasn't the ballet leap, until I finally remembered the ballet leap actual term...
The medical clue reads backward and is a little confusing - sounds like the answer you're asking for is a symptom of the diagnosis, yellowed skin. Could maybe say something like, "Yellow skin is a medical symptom of [insert correct answer here]." I get what it says as currently written, but it's awkward.
On the other hand, "juvenile" is a negative assessment of someone's behavior. Our junior project managers may act juvenile, but hopefully not.