Is there a word for “a word or phrase whose lack of understanding by a reader does not stop his understanding the gist of the sentence it’s used in”

Sample sentence:

This is an important set piece in the story as Kynes begins to admire Duke Leto, against all better judgment.
_{https://www.space.com/dune-movie-review}

I don't know the specific meaning of the phrase "set piece", though it seems to be a phrase that might easily have context-specific meaning. But my lack of understanding doesn't stop me understanding (or making a reasonably accurate guess at) the gist of the sentence: this (the aforementioned topic) is important in the story….

Is there a single word that describes such a notion?

My search of the English Stack Exchange generated these close matches, which are not the same as my question:

1. What is the word for "Unnecessary detailed information"?
   My question is not about words or phrases that are unnecessary detail: in my sample sentence, the phase "set piece" will likely convey meaningful information to a reader who understands the word.
2. What's the word for Unnecessary Complexity
   My question is not about words or phrases that add unnecessary complexity: in my sample sentence, "set piece" does not, and is not intended to add "complexity" to the sentence: it's a phrase that I think adds meaningful information to a reader who understands it, but it does not seem like it is used to intentionally obfuscate or jargonize the sentence as a whole.

Other hits were less and decreasingly relevant.

How the word would be used:

If the word I was looking for is foo, then I might use it in a sentence like so:

Even though I don't understand what "thneed" means, the word is just (a) foo, so I was able to understand the gist of the sentence "I was over the moon because I just got the thneed I'd been waiting for all year long!"