Baltic-Americans were delighted to read the informative and well-written editorial "Testing Glasnost" (Aug. 26). These Baltic demonstrators are merely the latest in a series of challenges to the logic of glasnost and they have much in common with earlier demonstrators seeking independence. The Soviet Union has frequently acquired its fringe republics and its national minorities by force of arms and then governs them against their will. Fortunately, the Baltic Nations, unlike many other national minorities, have a cause for independence in international law. However, in present circumstances having a good case counts for little in the face of overwhelming Soviet power.