I think a Japanese studio/Japanese actors are really needed if we want to truly show the more of the Eastern nuances that make Umineko even more complex. That said, I really want a western studio to do it, since they tend to have higher budget films. I think the Umineko movie would do well if it were directed by someone like Christopher Nolan. I just want a crossover between Inception and Umineko.
That said, I agree with @MrDent and @WitchOfGames. Umineko is too plot heavy to be put into a movie. It would have too much going on at once, and would probably end up confusing people. But if it were drawn out over a tv series, it would have more time to develop a coherent story. The manga already provides a great way of handling magical scenes, and I also thought the anime did a pretty good job with the whole red/blue truth goes.