I don't think it's an "art film" at all, it's just a standard mystery with a twist

Once you realize the movie's a pretty typical mystery tale with the added twist that we don't know the exact nature of the crime that's been committed (simply that it involves Elizabeth Taylor's character somehow), the whole thing kind of falls into place. We keep meeting all these weird crazy people because these are our suspects, just like most mysteries are filled with sketchy and quirky characters who are suspects and red herrings. In this case it includes the main character Lise, who might be the craziest of all, and we wait for the reveal as to whether she's the victim or the perpetrator.

People seem to think that this is supposed to be some deep pretentious "art" movie that doesn't make any sense on the surface, but I think that's a misconception simply because (1) the movie doesn't set up the plot very well from the start, and (2) most of the plot descriptions (even the "official" ones) appear to have been written by people after the fact who *also* had the misconception that it's some inscrutable "art" film and didn't realize the end is a huge plot twist (which is why so many of them just spoil it outright).

Honestly, if they'd simply placed one of those interrogation scenes at the very beginning, it probably would've set up the mechanics of the plot much more clearly from the get-go. Because this isn't actually all that difficult of a movie, it's just a twist on the standard mystery plot, sort of what J.J. Abrams does all the time.