I found the film Tár frequently baffling, and I'm putting these notes out here in hopes that somebody else who's seen it who's more attuned to this filmmaking style can enlighten me. Semi-spoilers.
1. Some movies can establish location clearly without title cards. This is not one of them. At one point Sharon implies that Lydia is keeping another apartment in Berlin besides the one they live in. Is that where Lydia is seen sleeping on a couch?
2. If, as Lydia avers at the film's climax, Eliot has her Mahler 5 score, does that mean that he's the person who snuck into her home and stole it earlier? And if so, is he also the person who, even earlier than that, snuck in and turned on her metronome in the middle of the night, and made her refrigerator hum? If so, why? And what is he doing in Berlin all this time? I thought he was in New York. (See, I told you this film needed title cards.)
3. Lydia says she's bruised because she was attacked. It looked to me as if she just tripped and fell while running up the stairs. Did I miss something, or is Lydia lying? If so, why?
4. Lydia invites Olga, the orchestra's probationary cellist, to an introductory lunch, where Olga tells of playing the Elgar cello concerto at the age of 13. I thought Lydia was going to summarily fire her for her horrendous table manners. Is ignoring these supposed to be a sign of how obsessed Lydia is by Olga?
5. Why is Olga living in what looks like a building untouched since it was bombed out in WW2?
6. Is it actually believable that a conducting student would disdain Bach's music because he was a white male with 20 children?
My interest was attracted to this film largely because it's about classical music. But unfortunately I can't evaluate the music in it, as I'm not very familiar with Mahler's Fifth and even less so with the Elgar cello concerto, two works I've never much cared for. I can tell you, however, that it would be most irregular to pair them on a regular concert: the combination would be far too much music, and heavy music at that, at once. I found that much more unbelievable than the moment in the plot that several critics have cited as unbelievable, which though unprecedented seemed to me to fit with Lydia's character.
I can confirm, in addition, that all the performers (conductors and instrumentalists) not directly characters in the story (onscreen or, in a couple cases, offscreen), and all the composers, past and present (except for a couple of the latter I hadn't heard of), are real people. So is the onscreen critic who interviews Lydia at the beginning: he's a real critic. (A fictional one would be unlikely to be so smarmy.)