With Sunday marking six months until the opening of the 2025 World Expo in Osaka, there is persisting concern about whether the construction of pavilions and other facilities will be completed in time. Achieving organizers’ target of 28.2 million visitors, 1.3 times the number at Expo 2005 in Aichi, central Japan, is key to covering the construction and operation costs of the event to be held on Yumeshima, a man-made island in Osaka Bay, from April 13 through Oct. 13. But construction of many of the pavilions has fallen behind schedule, with concern growing some will not be completed by the op…