Belgium’s coalition government faced a new threat after a French-speaking group--whose leader has brought down the last two governments--apparently won a majority in a local election. Early returns in the nationwide voting for local councils had no clear implications for the five-month-old government led by Prime Minister Wilfried Martens. But in a result likely to reopen tension between the nation’s French and Flemish speakers, a militant French group won nine of 15 seats in the Fourons--a cluster of French-speaking villages. A crisis could occur if the group’s leader, Socialist Jose Happart, is reelected mayor. He refuses to prove he can speak Flemish, the official provincial language, as he is required by law to do.