Key Takeaways:Waterdrop’s revenue fell 0.4% in the second quarter, but its profit rose fourfold as it controlled costs in what it described as a market filled with “challenges”The company’s recent Waterdrop Guardian AI initiative took a step forward with the signing of a new partnership with an unnamed insurance companyBy Doug Young The latest results from online insurance broker Waterdrop Inc. (NYSE: WDH) contained a steady stream of updates on both the company and its industry, providing a complex mix of both positive and negative developments for investors to drink up. On the positive side,…