Back when Central America's various wars and scenes of carnage were daily fare in newspapers and on the nightly news, many critics, including President Reagan, accused the media of exaggerating the conflicts. Lately, many of those same critics have been saying the media has not been paying enough attention to this area. In his address to the British Parliament in June, Reagan found it "strange" that "in my own country there's been little if any news coverage of [El Salvador] since the election" there in March.

If the quantity of coverage of Central America is such a burning issue, it is nothing compared to debates over its quality. To write, broadcast or even talk about the region has become an open invitation for abuse from the entire breadth of the political spectrum.

Still, last weekend, NBC devoted an hour of prime time to a program called "What Ever Happened to El Salvador?" Tonight at 8 o'clock, CBS opens a relatively new front in the media battle, until now largely restricted to reports on El Salvador and Nicaragua, with an hour titled simply "Guatemala." It is a bold treatment, in both subject and focus.

Paraphrasing a favorite point of former Secretary of State Alexander M. Haig Jr., correspondent Ed Rabel says Guatemala "is the big prize in Central America, the richest, most populous nation in the region we call our own back yard." After five years of stringent limits on U.S. aid, and a total cutoff of military assistance, to Guatemala on grounds of human rights abuses, the Reagan administration argues the battle against guerrillas there is close enough to home that our help is needed.

Guatemala's guerrilla war is the oldest continuous battle in Central America. It began after the 1954 CIA-organized military overthrow of a legitimately elected government that Washington and the United Fruit Co., owner of most of the arable land, thought had a pinkish tinge. The guerrillas, the still-ruling military, U.S. economic interests and the U.S. government, with a brief respite during the Carter administration, have not moved away from the struggle since.

Guatemala also has the only remaining large native Indian population in Central America: the Maya descendents that make up at least half the population. Their increasing abuse at the hands of land-hungry military officers and the savvy tactics of local guerrilla movements to incorporate them into their struggle makes them the new part of the Guatemala equation and the focus of the program.

"Guatemala" spends little time on charges by the Reagan administration that the guerrillas are Cuban-financed and trained and that a leftist victory would threaten U.S. strategic interests. Instead, it concentrates on charges, backed by such groups as Amnesty International and the State Department's human rights office that persons are being systematically killed by the government Reagan wants to support with guns and butter.

Many of the dead are Indians, and correspondent Rabel pulls no punches in assessing blame. The reason Indians are unrepresented and underpaid, their homes burned, their women raped and their children killed, he says, is racism.

One is hard put to argue. Listen to Fred Sherwood, a former president of the American Chamber of Commerce in Guatemala, land and factory owner and 36-year resident:

Guatemala has "a large labor market and the workers are very good," Sherwood says in a tour of the textile plant he manages. "You teach them, and they don't mind doing the same thing day after day" for the $4.50 he pays them. "Americans. . .they like variation. Here, the people do the same thing day after day, and they're very good."

What about claims by one peasant labor leader, shown in an interview, that 120 of his people were killed last month? "Well, in the first place, I very much question it because I don't think there's been 120 people of all types assassinated here in the last year. I mean, I'm not counting the peasants." But anyway, Sherwood continues, if any political figures were killed, it is perhaps because "these people are, I think, our enemies. They are against our way of life."

Well, are people oppressed in Guatemala, Sherwood is asked after the viewer has seen particularly gruesome selections of mangled bodies and crying Indian women. "I don't think so. . . . No one forces them to do anything, and I think this is just something that some reporters have thought up."

They couldn't have thought up Fred Sherwood, even if they tried.