WASHINGTON—Sen. John Kennedy (R-La.) and a trade group that represents small and regional financial services companies are urging U.S. regulators to act swiftly to fully implement a Trump-era law that requires foreign companies trading on American exchanges to meet U.S. accounting standards. On Dec. 18 last year, then-President Donald Trump signed into law the Holding Foreign Companies Accountable Act (HFCA Act) to protect investors from foreign companies that don’t follow U.S. audit standards. Congress unanimously passed the measure to mainly focus on Chinese companies that have come under intense scrutiny over fraudulent accounting practices. The Public Company Accounting Oversight Board (PCAOB) has been unable to inspect audit firms based in China for more than a decade. Beijing has refused to allow audit inspections of China-based companies, citing national security and privacy as reasons for noncompliance. The law, however, fixes that problem by forcing foreign companies to delist from U.S. exchanges …