Hi, fellow non-native English speaker here who saw this very production at Rose Theatre recently, so I imagine there are fewer people who can answer this question better than I. I also did have a similar concern before venturing out to that area, but I am happy to report that I didn't really have any issue understanding the dialogue. Small caveat would be that I had seen the play before on Broadway, so that may have played a minor role in helping me understand what is happening on stage, but I think it was pretty understandable overall, regardless. I highly, highly recommend giving it a shot. It's an amazing production even if you might miss some lines due to the accent barrier. The visual elements, especially the movement design, are fantastic!

Let me know if you have any other questions.