I can read only in English, so I’m limited in my ability to answer, but:
*I don’t look for realism as a goal in dialogue. Most people can’t (at least, don’t) talk as well as they write, much less as well as an accomplished writer writes. I like dialogue that is elegant, precise, imaginative, beautiful…“real” isn’t up there. A good author keeps it in the space of what people might say without digging around in what they actually do say most of the time.
*Using dialogue to define characters is tricky: in the early 20th century and prior, a lot of casual racism got published in the attempt to give characters an authentic patois, and I’m glad that phonetic spelling to reproduce accents, for example, doesn’t show up much anymore. Grammar, word choice, point of view, etc., can help portray a character’s background or circumstances, but they shouldn’t be shorthand for describing her/his mental or moral qualities: that comes from action.
*A quality I do like is using dialogue to differentiate between characters, and that’s a very difficult thing to do: so difficult it’s hard to think of a bright shining example of doing it well. Most characters in books sound a little different from each other but all tend to sound a lot like the author. Language is a personal thing and we tend to be rigid in our preferences, and suppressing subconscious tendencies with respect to sentence length, rhythm, etc., is (I imagine) almost impossible to do over the length of a book, especially if you have to do it in several distinct ways for multiple characters. Twain could do it, and it’s handled well in Grossman’s translation of Don Quixote too, but that’s earlier than the period you’re looking at. For that, the names that come to mind would be Stanley Elkin, John Cheever, Ursula Le Guin (R.I.P.), Zadie Smith, Richard Russo, Colson Whitehead, Gabriel Garcia-Marquez, and Michael Malone (probably the least-acclaimed of these names, but for this particular thing I think he stands out: his day job for a long time was writing for a soap opera, which may have helped him practice).
*If you like dialogue that is realistic, often funny, and drives the plot, read Elmore Leonard and Walter Mosley.
I’m probably quite a bit older than you, which skews the list of writers I know. Anyhow, as a non-scholarly reader, that’s what I’ve got to offer.