THERE'S GOOD NEWS from Ulster. Moderates there scored some gains in the by-elections held Thursday, and those who called for a massive vote to protest the new Anglo-Irish agreement were disappointed. That treaty sets up a bi-national commission to consider political, legal and security matters in the six counties of Northern Ireland. The commission is a forum, not a ruling body, and the treaty does not change the status of Northern Ireland as a part of the United Kingdom. The agreement has the strong support of parliaments in Britain and Ireland, but in the North cooperation has been opposed both by Protestants who want no dialogue with Dublin and by Catholics who do not recognize British sovereignty.

The by-elections were precipitated by the protest resignation, from the British parliament, of 15 Protestant members from Northern Ireland. Their leader, the Rev. Ian Paisley, announced that the new elections would let citizens demonstrate their "universal, cold fury" toward the agreement, and he called for a massive voter turnout. Meanwhile, Sinn Fein, the political arm of the Irish Republican Army, fielded candidates in four districts and they, too, opposed the treaty. In the middle, also running in four districts, were moderates of the Social Democratic and Labor Party. It has Protestant and Catholic members and strongly supports both the treaty and continued cooperation between Dublin and London.

Rev. Paisley did not get his massive protest vote. His Unionist parties received, on average, about the same number of votes they had in the last election in 1983, and Mr. Paisley himself lost supporters. In one district, the SDLP won a seat from the Unionists. Catholics, in general, voted for moderation over protest by a wide margin. Sinn Fein candidates lost a quarter of their votes measured against 1983, and the SDLP gained almost all of them.

None of this signals a miracle in Ulster. Fourteen of the 15 Unionist candidates who opposed the treaty were returned to parliament. But the voter turnout was not remarkable, and an angry message of protest was not sent. On the Catholic side, the move away from candidates condoning violence is heartening. The long-range goal of the Anglo-Irish treaty is reconciliation; prospects for achieving it are a little brighter.