A two-day symposium on U.S.-Japan economic problems ended here yesterday with an appeal by Japanese Ambassador Nobuhiko Ushiba to keep differences over "very narrow" trade issues in perspective.

Ushiba, recently designated chief representative for the multi-lateral trade negotiations (MTN), told a meeting sponsored by the Nihon Keizai newspaper he was "surprised, almost shocked" to discover the "intensity" of U.S. criticism of the persistent Japan trade surplus.

Yet after two days of frank exchanges among American and Japanese spokesmen, the gap in perspectives seemed unshaken: the Americans largely argued firmly they were doing all that is reasonably possible.

What it amounts to, Yale Professor Hugh Patrick said yesterday, "is a crisis of confidence on both sides." Where the U.S. insists that Japan -- for all of its protestations -- really keeps its market substantially closed to imports, "the U.S. in Japan comes across to the people there as a big bully."

Moreover, Patrick said, Japan has lost a sense of confidence in the ability of the U.S. leadership to manage its economy. In truth, he said, "neither side has shown it can manage or forestall a crisis."

Yasuo Takeyama, managing director of the Nihon Keizai, sometimes called the "Japanese Wall Street Journal," agreed in large measure with Patrick, emphasizing that Japan is no longer sure, after shaky U.S. postures in the Middle East, Africa, and Iran in the Middle East, Africa, and Iran "whether there is a conceptural framework for U.S. policy."

An even more specific sense of Japanese "insecurity" pointed out by Takeyama and other speakers relates to food and energy -- and the reliability of the U.S. as a supplier.

"I would appreciate if you remember," said Takeyama, "that the unexpected successive two crises of 1973 -- the soybean embargo by President Nixon and the oil-crisis -- left deep in the minds of Japanese a sense of insecurity to acquire the necessary foodstuffs and energy.

The question of food security has developed into a major issue in Japan. The theme of yesterday's discussion seemed to be that if Japan could get long-term supply contracts for soybeans from the U.S., smoother relations in other directions could be anticipated.

Another persistent theme explored by the Japanese is the need for the U.S. to curb inflation and to increase productivity. Success in those fields would do more to reduce the American trade deficit with Japan than persistent efforts to get Japan to take more imports, the Japanese said.