Robsteners has been kind enough to translate a great interview by spielfilm.de talking with Tai's trainer, Gary Johnson. There's all sorts of details from the set, including how Rob got along with Tai:
How did Robert Pattinson interact and work with Tai?
Johnson: Robert has a few close-ups with her and Tai thought him to be very likeable the first time she saw him. When Rosie is hurt he takes care of her. Robert never got loud with her and their relationship was adorable and easygoing. I think she liked him a lot.
It's a great interview, so don't miss the rest at Robsteners.