Officially, only the final touches remain to be put on Central America's Conta-dora peace treaty. But in private, Latin American diplomatic and United States congressional sources worry that opposition from hard-liners in the Reagan administration might lead Washington to actively oppose the agreement. The US, some say, could still block the accord by pressuring its regional allies, especially Honduras, to raise new conditions that might be unacceptable to the Nicaraguans.
The treaty is in the final stages of consideration by the countries that are supposed to sign it - all Central American nations and the four Contadora states that have worked out the plan, Venezuela, Colombia, Mexico, and Panama. On Oct. 15, signatories are slated to meet to propose any small adjustments they might want.
However, a current dispute over wording shows just how delicate the matter of small adjustments can be.
The Spanish text of the accord says that on Oct. 15 the Contadora countries will meet to make afinamientos in the treaty. The Nicaraguans maintain that this Spanish word translates as ''polishing.'' However, the official English translation of the treaty presented to the United Nations last week reads ''improvements.''
To Nicaraguan ears, ''improvements'' is an ominously vague term that could be used to justify the last-minute imposition of conditions unacceptable to them.
And most analysts wonder how the debate on Central America under way in the Reagan administration will be resolved both in the short run and after the US election.
When Nicaragua accepted the Contadora treaty last month, the US was put in an uncomfortable position. Observers say administration hard-liners have decided that the US cannot live with the Sandinistas, and that the Sandinistas must in the end be overthrown, either through the rebel contras and economic attrition, or through more direct US military intervention.
Reagan administration ''doves'' do not believe that the contras will succeed in overthrowing the Sandinistas and fear prolonged guerrilla warfare could result from direct US intervention. They distrust the Sandinistas but are willing to try a negotiated settlement.
The chief US dove seems to be Secretary of State George Shultz, while most hard-liners are in the Department of Defense. Among the latter are Undersecretary for Policy Fred Ikle and Deputy Assistant Secretary for Inter-American Affairs Nestor Sanchez as well as the National Security Council's Constantine Menges.
Doves and hard-liners are divided on Nicaraguan elections. Many at the State Department still favor some arrangement between Nicaraguan opposition leader Arturo Cruz Porras and the Sandinistas, although they are skeptical this would work. Hard-liners oppose any agreement.
The administration privately raised two concerns about the agreement last week.
1. The US fears the agreement would give Nicaragua a veto over US military aid to Honduras and El Salvador, with Nicaragua giving nothing substantial in return. Nicaragua responds that Salvador and Honduras would have a veto over East-bloc assistance to Nicaragua.
2. Without the participation of Arturo Cruz, Nicaraguan elections are a farce , the US says. It also holds that the Contadora accord, as it now stands, would ratify what it views as oppressive, Marxist rule in Nicaragua.
Officially, the US complains treaty measures for verifying the inflow of arms and aid to guerrillas in the region are too weak. Honduras is also unhappy with the measures. Diplomatic sources say US Ambassador Jeane Kirkpatrick exerted ''strong pressure'' on the Contadora countries before they presented the treaty to the UN.