if it weren't for Wikipedia's detailed plot I wouldn't have understood most of what this movie was about

it's one of those movies that makes sense after a second viewing. Happened with his Naked Lunch adaptation.
I had to read the wiki page to realize what was wrong with the final "performance" on a dead body

I couldn't understand like a fifth of the dialogue, but I thought the plot itself was fairly straightforward. To each their own of course.

Wow, thought I was the only one who had this problem with this movie. Not only is the plot muddled and overstuffed, I couldn't understand half of what the actors said as they were all whispering under their breath.

Like you, I had to read on Wiki on what I had missed. I do want to watch it again with subtitles on some time, but from what I experienced, it was an incredibly dull, uneventful film. When the ending happened, I was like "WHAT, THAT'S IT?!"