Few people seem to be quarreling with D.C. City Council member Douglas E. Moore for sending a letter in French to D.C. School Supt. Vincent E. Reed to protest foreign language cutbacks in the city's elementary schools.

Rather, the quarrel seems to be with the French Moore used. It's all wrong, some local French scholars say privately, contending that there are at least 18 to 24 errors in the page-and-a-half long letter. Moore says he wrote the letter with the assistance of some "technicians" - city aides who have studied French in the past.

Moore said in the letter that he hoped Reed, who can neither read or speak French, would "realize in reading this letter the importance of foreign languages in the schools." Reed said he did, but mainly because he took Spanish in high school and college.

Now, with last-laugh chuckles in their throats, some of Reed's supporters are saying that Moore needs to realize not only the importance of learning a foreign language, but learning it correctly.

The criticism doesn't bother Moore, who has since received letters in Spanish and Vietnamese, which he says echo his concerns.

"If you ask me about my grammar, I ain't ever had enough of nothing," Moore said. "The purpose of language is to communicate. I think he got the point."

Moore's probably right. How else can one explain the fact that the lead paragraph in the Post's story about the letter, also written in French, contained, in one expert's opinion, at least two mistakes.

Despite the perennial chatter about how strong a grip the Metropolitan Washington Board of Trade has on city government, the board itself apparently has been dissatisfied with the returns it has been getting from the politicians its members have supported financially.

So in the next few months, the board plans to set up its own political action committee, in the style of committees that have been established on the national level by labor, the medical profession, home builders and others. The sole purpose of the committee, executive vice president Clarence Arata says, is to contribute money to political campaigns and organizations.

Arata said that in the past there has been "a lack of focus" to the support of candidates by board members. The decision to set up a political action committee was inspired by the success of similar organizations established by chambers of commerce in other cities, he said.

Board of trade members are already the major bankrollers of most campaigns in the city, and the board has more registered lobbyists of city government than anyone else in Washington. Establishing an action committee would be to add still another dimension to the amount of funds that the trade board would be able to inject into local politics.

Without the action committee, trade board members would be more limited in the amount of money they could contribute. In the race for mayor, for instance, an individual could give no more than $1,000 to a candidate. His corporation however, could give another $2,000 to each mayoral candidate.

The establishment of an action committee could give an additional $1,000 to each mayoral candidate and unlimited amounts to party organizations such as the D. C. Democratic Senate Committee. There are no limits on the amounts that either individuals or corporations can contribute to a political action committee.

One of the biggest obstacles Marion Barry faces in testing out his chances for mayor in 1978 is a provision of the city's election law that would require Barry to relinquish his seat on the City Council the moment he declares his candidacy for mayor.

For the past year, Barry has been walking on political eggshells, trying to get the word out that he's interested in the job without really saying he's interested in the job. Last month, Council member Arrington Dixon (D-four) seemed to have the solution when he introduced a bill that would repeal that section of the election law.

Now, however, the word around the District Building is that voting on such a bill could create a problem for council members who would benefit from it, in the same way that many lawmakers are prevented from voting pay increases for themselves.

Such an interpretation of the law could hurt the bill's chances for adoption, especially if the mayor decided to veto it. Nine votes would be necessary to override. All of the council members whose terms don't expire until 1980 and are thinking about running in 1978 could be prevented from voting on the measure.

That would automatically nix the votes of Barry and Dixon, who is widely talked about as a candidate for city council chairman, along with John Wilson, another possible council chairman hopeful. All would probably vote for passage of the bill. That leaves only 10 votes on the Council. Perhaps enough to pass the measure - but not enough to override.

With the first chilly days of autumn bringing some of the most serious maneuvering to date over possible Democratic mayoral candidates for 1978, it might be worthwhile to regularly check the latest names dropped and combinations imagined. Here are two that are floating around these days:

D.C. Del. Walter E. Fauntroy, out of the goodness of his heart and his concern for the welfare of the city, will run for mayor. Sources close to Fauntroy doubt that very seriously, but say Fauntroy has not totally ruled it out.Local political pundits wonder why Fauntroy would bother to leave his comfortable job on the Hill to come to deal with the city's problems.

Marion Barry, if he fails to get the backing of Fauntroy, will choose the Rev. David Eaton, pastor of All Souls Unitarian Church, as his slate mate and choice for City Council chairman. Eaton is very close to Fauntroy and could neutralize opposition to Barry from the congressman, the notion goes.

Many of those closeose to Fauntroy say they don't take Eaton seriously and would never expect him to buck Fauntroy, even though the minister has a draft-me-for-mayor committee in existence.