His film of the hour at Cannes is The Man From London (Londoni férfi) and is based on the novel by Belgian writer Georges Simenon. Tarr adapted the film with László Krasznahorkai. The film production itself seems to fit the above description of agony in the making from threats to shut down the production, lack of financing and finally completion.
The film is about a man who witnesses a mystery, and nothing else is known at the moment. It stars Tilda Swinton opposite Czech actor Miroslav Krobot. The international ensemble cast also features British actress Leah Williams, and Hungarian actors Janos Derzsi and Istvan Lenart. German cinematographer Fred Kelemen is the director of photography.
Tarr has been written about extensively and here are some links to web articles about the artist.
Brightlights Film Journal