-Analysis- BUENOS AIRES — The current strained relations between Argentina and Brazil may hide a problem about the region that goes deeper — and wider. Argentina’s scarce participation in the July 8 Mercosur summit is the latest signs of the South American trading bloc’s precarious state. The absence of the Argentine president, Javier Milei, and resurgent political divisions between the two neighbors (with this time a right-wing president in Buenos Aires and a socialist in Brasilia) are part of a bigger and so far irreversible reality: That Mercosur is more a source of discord than unity. For …