So I am noticing the term "structure" in coffee descriptions. Here are just a few examples I quickly found.
"Sweet-tart structure with bright, winy acidity; viscous, creamy mouthfeel." - Paradise re: Nicaragua SL28
"The sweet cocoa and caramel nose leads into a medium-bodied cup, transitioning through the palate building more structure along the way." - Lusso re: GMC
"Sweet in structure with lively acidity; velvety mouthfeel." Coffee Review re: Klatch Guatemala Concepción Buena Vista

I realized, I don't know what this means. What is structure in coffee? So I went the google machine and asked, not much info to easily find. Then I went to the HB google machine, not many threads about it there either. So I googled "what is structure in wine."

Wine Enthusiast has this to say: "The structure of a wine is the relationship between its tannins and acidity, plus other components like glycerol and alcohol. It's a complex concept that requires a pretty nuanced understanding of wine."

Ok? So coffee has some of those components but not all of them. Maybe understanding structure in coffee requires a pretty nuanced understanding of coffee too? Can someone help me to understand it? Roasters seem to be using the term like everyone understands what structure means. I don't, and I bet I am not the only one. Thanks in advance ya'll.

I'm sure it's a borrowed wine term. How I understand it is the structure of coffee (or wine) are the characteristics in more broad strokes than fine detail that are like building blocks that work together to make the coffee. I'm not certain of the terms within structures or even if there are any set but if you look at a flavour wheel the inner circle has the broad terms like fruity, sweet, floral etc... and I would think these would be best described as the structure of the coffee. A coffee doesn't have a jasmine structure but rather a floral structure with Jasmine notes

Now with that said your first example is a "sweet-tart" structure which might be better put as a sweet-sour or sweet-acidic structure to match the flavour wheel (depending which one your looking at of course) so its probably less about what terms you use and more about where they fit and consistent use of them where the roaster has the freedom to express the terms they wish.

"The sweet cocoa and caramel nose leads into a medium-bodied cup, transitioning through the palate building more structure along the way". This one is makes full use of wine terms and to me is a little over the top. IMO in coffee we prefer aroma over nose and I don't think it looks good adopt all these wine terms when we already have terms to describe the same thing. But I would say the identified structure is sweet and cocoa but caramel to me is not a structure as it fits it sweet. So I would anticipate the sweet and cocoa structure becomes more developed where a caramel and perhaps chocolate are features of the sweet and cocoa.

"Sweet in structure with lively acidity; velvety mouthfeel" I think this one is odd too as it seems the structure is sweet-sour (not just sweet) but in coffee we like to describe acidity as lively. I think the guy who wrote it is just playing with ways to describe this. I walk away from this thinking sweet is more dominate then I see that it has lively acidity so I think the acidity is more dominate and sweet muted. So it's confusing to me and I don't know which is it sweet or acidic as both are being used to show intensity.