The president’s vision for reshaping global trade is falling into place, but he is embarking on an experiment that economists say could still produce damaging results.Over the last six months, the United States has left behind the global trade order that persisted for decades in favor of something drastically different and largely untested. Formidable economies like the European Union and Japan have abruptly made peace with higher tariffs on their exports, acquiescing to President Trump’s demands in order to avoid damaging trade wars and to coax even steeper U.S. duties down just a little bit. As major economies fall in...