Rep. Joseph L. Fisher (D-Va.) is returning home today from a 12-day trip to four foreign countries with "a depth of understanding I could have gotten no other way."

Fisher was one of 14 members of Congress who were official delegates to the Interparlimentary Union conference that ended yesterday in Lisbon.

Sen. John Sparkman (D-Ala.), the leader of the American delegation who has been attening IPU meetings since about 1954, said the benefits of this year's meeting in Portugal were "the same as always, development of better understanding and peace."

Sen. Abraham Ribicoff (D-Conn.) said the highlight of his week of debate among legislators from more than 60 nations was agreement on a statement of terrorism. Some other members of the U.S. delegation credited Ribicoff's emotional appeal for an end to international terrorism - "Killing innocents," he called it - with winning agreement from a committee that included members from Israel, Jordan, Syria, Yugoslavia and Hungary.

Ribicoff told the delegates that one of the victims of the terrorist attack on an Israeli bus last month was Gail Rubin, the niece of his sister-in-law. She was a photographer who taking pictures on a beach.

"The Jordanian representative stood up and expressed his sympathy," Ribicoff said.

Ribicoff said he considered it a major victory that the debate "didn't bog down" on the Palestinian-Israeli issue "as it usually does at international meetings."

The resolution approved by the delegates "recognized terrorism as a universal problem. It calls for all countries to work against terrorists by agreeing not to give them sanctuary, while allowing each to impose different sanctions," Ribicoff said.

Sparkman's major statement at the conference was a counterattack on a Russian resolution that condemned the neutron bomb.

Sparkman, who is chairman of the Senate Foreign Relations Committee, denounced the proposal as "a one-sided propaganda exercise. The Soviet proposal calls for prohibition of a single type of nuclear weapon that may be deployed in the European theater while ignoring the many other nuclear weapons already deployed there or now being deployed."

Sparkman, Ribicoff and Rep. Lionel Van Deerlin (D-Calif) and their wives were among 14 members of the 46-member U.S. delegation who left Lisbon early Friday, before the conference ended, to return to London, where the trip began 11 days ago.

Sparkman said the American delegation to IPU meetings has "nearly always split up and gone back to the first stop on the trip to wait for the others to catch up.

Ribicoff said one of the reasons he liked the idea of going to the IPU was inclusions of stopovers here at both ends of the trip.

Yesterday, Sparkman, Ribicoff and Van Deerlin had lunched with U.S. Ambassador Kingman Brewster, a meeting that Sparkman described as "very useful."

Back in Lisbon, it was a quiet day for most of the American party. Three legislators a Hended the final IPU session.

The other six congressmen and Sen. William L. Scott (R-Va.) had the rainy and foggy day off for sightseeing.

Last night many of the Americans planned to go together to a Lisbon restaurant. Except for official receptions - and there were plenty of them given by various national delegations, though none by the Americans - it was the first time the Americans had spent a social evening together this week.

"They were a rather subdued group," said Arthur Kuhl, the assistant Senate secretary who was in charge of distributing expense money for the party.

Many of the delegates remarked on the fact that the activities at the conference were being recorded by a reporter, and several complained that the stories ignored the substantive issues debated at the conference.

Kuhl's reaction to the stories echoed comments from several members of the congressional delegation, when he suggested that the reporter should "go take a look at the law of the sea meeting in Geneva. They sit around for weeks and do nothing."