This gathering of about 350 delegates to the Palestine National Council and more than a thousand observers and guests can be compared to a family reunion--albeit a flawed one--and, like other such reunions, it is less placid than appearances would first suggest.

Amid the hugging and kissing, something is amiss. It is not just the aging of the participants and the increasingly obvious absence of meaningful numbers of young Palestinians amid the graying and paunchy veterans at their parliament-in-exile.

Unity, the theme of this PNC meeting and of the Palestine Liberation Organization throughout its checkered history, is being paid for at the price of immobilization.

"We call this the lam PNC," a supporter of PLO Chairman Yasser Arafat said, explaining that lam was a mixture of la, the Arabic word meaning no, and nam, which means yes. By that he meant that the PLO was torn between its desire to get on with negotiations, to settle for even the smallest patch of land where a Palestinian flag could be flown, and the knowledge that even this seemed beyond its grasp, that revolutionary rhetoric comes easier than revolutionary accomplishment.

But there is also a new impression of loneliness, of amateurish improvisation and even occasionally self-defeating sloppiness. For example, the official conference booklet has a bad French translation--and an atrocious English version--of its Arabic text. One English sentence describes the council members as representatives of "various heavily armed desperado groups," a definition not so far from the Israelis' blanket description of the PLO as "terrorists."

When the wording was pointed out to an embarrassed PLO official, he said apologetically, "You know, we are no longer in Beirut." It was his way of saying that not only had the Palestinians lost as close to a capital as they were likely to have for a very long time, but also a foothold in a modern, efficient, westernized society.

The Soviet, Tunisian, Indian, Syrian, Moroccan and other foreign guests who addressed the council today used the antiimperialist, anticolonialist vocabulary coined more than a generation ago at the first nonaligned summit at Bandung in Indonesia.

"The same rhetoric, the same hyperbole," said Arab-American publicist M.T. Mehdi, comparing this council meeting to two others he had attended over the years. "Perhaps they have moved a little bit to a more rational attitude, but not a single new idea will come out of this that will affect President Reagan's decisions on the Middle East. It will have no impact in the real world."

"Remember, we are dealing with an illiterate society operating in the ways of the 16th century," he continued, "and expecting to catch up to the 20th century in only 20 years. It took the West some 400 years."

Yet for some delegates the real game is not so much winning this or that point about contacts with the Israeli left, the Egyptian opposition and government or even what, if any, mandate King Hussein of Jordan should be granted to speak for the Palestinians if the negotiations about the future of the Israeli-occupied West Bank and Gaza Strip proposed by Reagan ever begin.

Rather the stakes involve Arafat, at once a revered but often resented father figure both in good times and bad--or, perhaps more accurately, in bad times and worse. Even Fatah, the mainstream group he fashioned to dominate the PLO, at times resents his often high-handed ways.

For example, an old left-wing lieutenant of Arafat's named Abu Saleh was dropped summarily from council membership. His constant carping and Syrian-directed maneuvers had gained Abu Saleh few friends and less sympathy among the Fatah rank and file, but they nonetheless objected to Arafat's arbitrary handling of his case.

Beyond such seemingly secondary questions lie Arafat's efforts to have the council in effect renew his leadership by plebiscite and his critics' determination to limit his new mandate to keep a closer watch on his increasing penchant for solitary diplomacy.

One disabused younger PLO official said gloomily, "We are becoming like all other Arab regimes with their lifetime presidents."