From what I recall that’s about all we know about her from the books. She’s slightly more than a blank slate, much like most of the supporting snd background characters.
I really disagree there - that's really underselling the books' characters, and I'd like to make a number of points as to why.
First, this isn't an argument I've made, and I forget where I read it, but Rowling's character cast is excellent from a writing standpoint, or rather, a memorability standpoint. There's a reason why, even when we don't know that much about a character, we still remember them in the books, and a lot of it's down to the naming conventions. Again, the people who wrote the article (which I can't recall, so I'm afraid you'll have to take my word for it), pointed out the use of language for the characters. There's a reason why even if there's not much to say about a character per se, their names are easy to remember. We have "Cho Chang" and "Colin Creevy" or "Luna Lovegood" for example (alliteration), or Cornelius Fudge or Neville Longbottom (esoteric surnames), or thematic forenames (e.g. how every member of the Black Family is named after a constellation - Sirius, Andromeda, etc.)
Second, I'd hardly call Cho a blank slate. I mean, here's a tertiary character, who appears in at least four books, and that she gets that amount of characterization at all is still quite impressive.
Third, and this is arguably the crux of the argument, I really, REALLY disagree about the characters being blank slates, and I'd like to use a few points.
First, the Weasley family. That's seven children (you can pair Fred and George, so more like 6.5), plus Arthur, plus Molly. Every one of them with the exception of Charlie has a defined personality, and even Charlie has a defined backstory. That's nine characters in one family by itself that's fleshed out over an entire series. There's more characterization in the Weasley family alone than entire casts in similar series.
Second, I'd argue that the fact that we can remember so many names off the top of our heads is testament to the depth of the characters, but name any character from the series, and chances are you'll have at least a mini-biography behind them. Heck, go to the wiki if you don't believe me.
Third, and this is more of a personal point than anything else, having read stuff like The Magisterium and Keeper of the Lost Cities recently, both of which rely on the magic school trope, it's astounding how facile they are compared to Harry Potter, and no, that isn't nostalgia talking. Obviously, a key difference here is that I read HP at the intended age, but even then, being as objective as possible, Magisterium is just banal in its characters and worldbuilding, and Keeper is absolutely wretched (so far). It's part of why I agree with the notion that people should watch/read bad films/books to get an understanding as to what makes fiction work, but when you compare and contrast how HP handles its characters and how other series, well, don't, then I think it's easier to appreciate them all the more. I mean, for instance, I can name pretty much every Hogwarts teacher, as well as a fair no. of Magisterium teachers, but the difference is that in Magisterium, I cannot, for the life of me, name a single character trait for the masters (bar one possible exception), whereas practically every Hogwarts teacher by themselves has a distinct personality. I mean, we get six Defence Against the Dark Arts teachers alone through the series (five if you exclude Snape), and all of them are memorable in their own ways. There's more memorable teachers for a single subject in HP than the entire teacher rosters of the afforementioned contemporaries.
Fourth, and another personal point, writing is hard. Really hard. I know, I mean, I've been doing it for ages and done courses for it, and it's freaking hard (to do well). On the subject of characters, not only do you need to get a character, and flesh out their backstory (which is hard enough), but then you've got to convey that backstory over the course of a story/stories without overwhelming the reader, and I still don't think I'm there yet (probably never will be), since the last two stories I wrote/am writing had to rely on flashbacks to get some of that backstory across. So considering just how many named characters there are in HP, and how many of them get backstory at all, it's astounding just how impressive it's pulled off.
Anyway, that's just my take. Part of the reason why is indeed, coming off Magisterium/Keeper, arguably the best thing about reading such books is that it helps me appreciate the difference between good writing and bad writing all the more.