As the actual event of German unification unfolds on the world's TV screens, many observers view the spectacle as a precursor not only of renewed German might, but of enlarged clout for the European region as a whole.

Only a couple years ago, the continent suffered from what some called ''Eurosclerosis.'' Now, ''Europhoria'' has overtaken the 12 present members of the European Community. They exude confidence that ''the decade of Europe'' is underway.

But as ''Europe 1992'' with its single, unified market of 320 million comes close to reality, it is clear that much more is at stake than mere abandonment of internal tariffs. Already feeling the pain of Japanese superiority in some industrial high-tech applications, the new worry in Washington is that America may drop to No. 3 behind Europe.

A main impetus for the entire Europe 1992 adventure was the realization by leaders such as European Community President Jacques Delors that Japan had seized a lead in high-tech manufacturing and cut into European markets. European leaders perceived the need to do something dramatic to improve their own high-tech potential.

As seen from Brussels, the United States never evolved a high-tech policy to match Japan's. And the Brussels policy makers concede that there isn't any one European nation -- not even Germany -- likely to keep pace with Japan. But linked together, one European told me, ''we'll do our damnedest. We probably will never catch Japan, but we may do better than the United States is doing.''

At a Brookings Institution seminar, Georgetown University Professor Gary Hufbauer raised the specter of the single market spawning ''a new generation of European industrial and banking giants'' that will have a distinct advantage in financing high-tech research and development.

''European firms will now join Japanese firms in pushing U.S.-based firms down in the rankings of industrial and financial giants,'' Hufbauer said at the seminar, jointly sponsored by the Council on Competitiveness.

He suggested the need to consider further relaxation of the Sherman Anti-Trust Act and the Glass-Steagall Act (on banking) ''so that top {American} firms can combine and better compete in world markets.'' Europe is more casual about such things. Douglas E. Rosenthal of Coudert Brothers made the point that the EC authorities are promoting mergers and ''don't pay enough attention to cartels.''

Because Europe actively seeks additional foreign investment by high-tech companies, Hufbauer predicted that U.S. high-tech exports to Europe will gradually fall off as the EC builds capacity on its own soil. Because that would represent a transfer of American jobs to Europe, the trend contains the seeds of increased tension between the United States and the EC. Relations already are at somewhat of a raw edge because of disputes in other trade areas, including agricultural export subsidies and telecommunications.

On all these sore points, Deputy United States Trade Representative Julius L. Katz took an optimistic view. He told the meeting that while ''we have a lot of bilateral problems with Europe,'' the question of Europe 1992's discrimination against the outside world would probably be outweighed by ''the trade creation effect'' of the enlarged market.

Nonetheless, while Europe 1992 opens up exciting new vistas within Europe, more question marks than answers have been raised for the rest of the world. If Europe makes substantial gains in high-tech, Hufbauer thinks that Brussels, rather than Washington, could become ''the custodian of the international economic system.''

Hufbauer's fellow panelists agreed that Europe is destined to have new clout, but were less sure that Europe would emerge as the next dominant economic power and guardian of the system. Sylvia Ostry, a former top Canadian government economic adviser, observed: ''There is very little interest in Europe in systemic issues. They are very much preoccupied with reshaping Europe in the 21st century.''

But she's in accord with Hufbauer that America is in for stiff high-tech battles with Europe, because Brussels makes clear to American companies that if they want the benefits of the single market, they should create or expand an actual presence there. She sees this as the beginning of an era of competition for ''good'' investment -- especially in high-tech.

Meanwhile, earlier fears that Europe 1992 might become ''Fortress Europe,'' erecting new barriers against outsiders, have been only partially assuaged. For example, Europe's powerful auto moguls appear determined never to allow a totally free market for cars.

Strict limits will remain on imports from Japanese auto ''transplants'' located in Ohio and Tennessee to Europe. Under international trade regulations, these are American cars. But don't look for Ford and General Motors, well-established within Europe, to complain that it's unfair.