The Reagan-Gorbachev summit in Geneva last month is cause for reserved enthusiasm, five representatives from Western Europe and Japan said last night in a forum on the effect of the summit in their countries.

Amid statements that the summit was "positive" and "highly significant" the five speakers told the audience of about 100 that "something was acheived" by the first meeting of the American and Soviet leaders in six years.

"We can settle [after the summit] for a limited breakthrough in East-West relations," Andrew Palmer, a member of the British government's Foreign and Commonwealth Office told the Lamont audience.

Geneva was a positive step toward improving East-West relations but did not signal complete detente, he said. "Summits have been followed by letdowns," Palmer said.

The five foreign service officers from the West Germany, France, Great Britain, Italy and Japan who spoke are fellows at the Center for International Affairs.

"The central issue, that of arms control, is still not solved," said Ukeru Magosaki, director of the analysis division in Japan's Ministry of Foreign Affairs. But Magosaki added that it was a real effort for Gorbachev to come to the summit.

Sense of Relief

"There is a sense of relief at the idea that a dialogue has started again," said Ferdinando Nelli-Feroci, counselor at the Italian Ministry of Foreign Affairs. "But notes of caution are to be drawn," he added.

But Nelli-Feroci said that the failure to include European nations at the summit hampered its usefulness. "If there was someone absent in Geneva is was definitely Europe," he said.

Bernard Bajolet, a counselor at France's Embassy in Rome, said the Geneva meeting was "a stage, not really a start nor an end [in bettering East-West relations]."

"In the short run the summit is positive, but it could turn out to be dangerous if we keep up illusions," Bajolet said.