BUENA PARK, Calif.—The City of Buena Park’s goal to pump up its sagging entertainment core—known mostly for Knott’s Berry Farm—continues to see delays, as a long-planned new theme park where kids and adults alike could frolic alongside butterflies, remains stalled in legal limbo. The story starts when city officials toured a “Butterfly Pavilion” in Arizona and were so enamored with it, they decided they needed one of their own. They sold their aging Movieland Wax Museum and its land for $2.45 million to Rubin Stahl, a world-renowned developer of shopping centers and entertainment attractions. Stahl went on to form a separate company to develop the land and hired a construction company called Outside the Lines to build the attraction. The construction company broke ground in 2016 and everyone planned for a 2018 opening date. But nothing has gone as planned. Today, Stahl’s and the city’s vision—a 17,500 square foot enclosed …