HONG KONG—China’s plan to tighten scrutiny over mainland companies’ overseas share sales is likely to ease the regulatory uncertainty that roiled financial markets this year and stalled offshore listings, bankers and analysts said. But the securities regulator’s new filing-based system, designed to rein in once freewheeling Chinese listings in the U.S. market and elsewhere, leaves open questions about rule enforcement and compliance criteria, they added. “The new rules represent a comprehensive, systemic and market-oriented regulatory upgrade,” investment bank China International Capital Corp. (CICC) said in a note, but added they contain “some items that need further observation, and clarification.” The China Securities and Regulatory Commission published draft rules late on Friday requiring filings by companies seeking offshore listings under a framework to ensure they comply with Chinese laws and regulations. Companies using a so-called variable interest entity (VIE) structure will still be allowed to seek offshore listings as long as …