President Carter welcomed his wife, Rosalynn, home yesterday, and said her two-week trip to seven Latin American countries was one "of great significance to our country and to the peoples she has visited."

Carter said the First Lady's goals in dealing with the leaders of the countries, "as laid out by the State Department and the White House, have all been caried out almost to perfection."

Mrs. Carter's Air Force 707 jet landed at 4:20 p.m. at Andrews Air Force Base after a 12,000-mile journey that took her to Jamaica, Costa Rica, Ecuador, Peru, Brazil, Colombia, and Venezuela.

A large sign saying "Bienvenidas (Welcome to) Washington" was on the airfield as Carter, their daughter, Amy, and Secretary of State Cyrus R. Vance bounded up to the plane to greet Mrs. Carter and Vance's wife, Grace, who had accompanied her. Vice President and Mrs. Mondale and national security adviser Zbigniew Brzezinski also met the plane.

Mrs. Carter, alluding to the speeches she has been giving the last two weeks, said, "Es un gran placer para mi (it's a great pleasure for me)." She also used the language of a diplomat in referring to her husband: "I look forward to consulting closely with him on a regular basis."

Declaring that "we are ready to develop balanced, natural, normal relations" with Southern Hemisphere nations, Mrs. Carter told the President, "They love you in thee Caribbean and Latin America."

She said that on the major issues she discussed with the foreign leaders - human rights, nuclear nonproliferation, economic development and arms control - "I think we've made progress."

On her flight from Caracas to Washington Mrs. Carter said that "at times they told me things I didn't want to hear."

She did not specify these, but clearly one was a refusal by President Ernesto Geisel of Brazil to agree to sign the 1969 American Convention on Human Rights, which President Carter signed earlier this month.

Prime Minister Michael Manley of Jamaica and President Francisco Monrales Bermudez of Peru told her they would sign it, and President Carlos Andres Perez of Venezuela informed her yesterday that his nation had signed and ratified it, she said.

Leaders of those three countries and Costa Rica, Colombia, and Ecuador told her they are willing to discuss human rights when the meeting of the Organization of American States starts Tuesday on the Caribbean island of Grenada.

Asked why Brazil had balked, Mrs. Carter said that all countries in thee United Nations (including Brazil) had signed its Declaration on Human Rights, "and some countries think this is sufficient."

Mrs. Carter said, however, she thinks the American Convention, which calls for an inter-American court on human rights and compensation for victims of injustice, "is very important."

Terence A. Todman, assistant secretary of state for inter-American affairs, who accompanied Mrs. Carter on the trip, said that if the convention were ratified by the requisite 11 nations, the Inter-American Human Rights Commission would become more active. Until Perez' announcement yesterday, only Colombia and Costa Rica were known to have ratified the agreement.

The commission, which is supposed to look into alleged violations of human rights, is small and "inadequately financed," Todman said.

Brazil has been at odds with the Carter administration because of a State Department document made public in March that critizied Brazil for not providing trials for political prisoners.

Another point of contention has been U.S. opposition to Brazil's plan to buy nuclear reprocessing equipment from West Germany. In reprocessing nuclear fuel, the plutonium by product can be used in making atomic bombs.

Todman called reprocessing "the most delicate issue" that Mrs. Carter discussed on the entire trip. "They didn't say they would change their position, and we didn't change ours," he added.

Mrs. Carter said last week she was "really pleased" with her nuclear talks with the Brazilian leaders and believed they "took into consideration" her suggested alternatives to having a nuclear reprocessing plant of their own to replenish their uranium supply.

The options she proposed were for Brazil to obtain nuclear power plant fuel from the United States, or from a reprocessing plant that would be under international control in another country, or from new technology using thorium, still being developed, which avoids the production of plutonium.

Mrs. Carter said she discussed with Venezuelan President Perez the U.S. exclusion of members of the Organization of Petroleum Exporting Countries from special trade advantages on their manufactured goods. Venezuela is an OPEC member.

"I told him how much we appreciated Venezuela's being a reliable source of petroleum" during the 1973-74 Arab oil embargo, Mrs. Carter said. "But I said it's a difficult issue in our country because people didn't like the quadrupling of oil prices. I told him I couldn't promise him we would repeal" the exclusion provision in the 1974 Trade Act, "but we were reviewing it."