IN OUR ACCOUNT of the final vote on the second Panama Canal treaty in this space on Wednesday, we had it almost all wrong when we observed that "surely the most telling scene took place the previous day when the final compromise on the DeConcini reservation was struck - by a handful of senators, maintaining their own exclusive channel to Panama, with the administration's people standing in the corridor outside." There were news accounts of some such scene on Monday, with administration lobbyists on the outside, while Senate leaders bargained behind clsoed doors. But we are advised, persuasively, that the real compromise was worked out at a meeting on Sunday initiated by Undersecretary of State Warren Christopher and including the Panamanian ambassador, Sen., Robet Byrd (D - W.Va.), Frank Church (D-Idaho), Alan Cranston (D-Calif.) and Paul Sarbanes (D-Md.), and William D. Rogers, now a private lawyer and formerly an assistant secretary of state for Latin American affairs. Mr. Rogers had actually been recruited by the administration to serve as an "exclusive channel" between the Senate and the Panamanian government, and Mr. Christopher, we are told, was a substantive participant at almost every stop along the way.

So we stand corrected. The administration was not so insulated from the proceedings as we had supposed, and the president and his lieutenants deserve more credit than our account gave them for their role in the final hectic scramble to preserve, in the final vote, the slim two-vote margin by which the first treaty passed. That brings us to a large question, also raised in this space on Wednesday - the question of what the protracted struggle over the Panama Canal treaties tells about the president's competence in the conduct of foreign policy, at home as well as abroad, politically as well as diplomatically. On Wednesday, we observed that "we cannot recall a similar instance in which an administration had so lost control of a vital international negotiation, or one in which, given the administration's own performance it was probably to its advantage that it be on the outside." And we added: "It goes without saying that this does not bode's well for the other difficult political/diplomatic negotiations in which Mr. Carter is involved."

Is that too harsh, in light of the facts of the administration's involvement, as we now understand them? In fact, our second thoughts are a lot closer to our first thoughts than they are to the ebullient postmortems and the projections of new "momentum" offered by the administration. It is never easy, of course, to quarrel with success, and there is no denying that the administration succeeded against heavy odds - if you take seriously, as Jody Powell does, the very early nose counts of Senate opposition to the "Panama giveaway," before there were detailed treaties to talk about. But it is also a fact that earlier this year some opponents were virtually conceding defeat - and that in the end the outcome was agonizingly close. Yes, it can be argued that the problem of the Deconcini reservation - compounded by its author's complusion to explain it in increasingly troublesome terms - was skillfully resolved in the second treaty. But a large part of the problem was created by the president's handling of that reservation the first time around. Again, it may have been sound tactics for Mr. Carter to let the Senate leaders deal more or less directly with the Panamanians in the final negotiations. But it remains a fact that in the end Sen. Byrd had become the "captain of the ship" - in the words of the Panamanian chief of state, Gen. Omar Torrijos.

So we are not quite ready to accept the "appropriate conclusions" that the president's national security adviser, Zbigniew Brzezinski, would have us draw from the president's handling of the Panama Canal question: "He takes on hard issues, he sticks with them, and he prevails." And we are not entirely reassured to hear from Mr. Brzezinski that "we're going to deal with other issues the same way." True, Panama was a hard issue. To his credit, the president did stick with it. And, in a manner too precarious for much comfort, he prevailed. But all that can be safely concluded from the Panama cliffhanger, in our view, is that the president has survived. It remains for him to demonstrate his mastery of foreign policy another day.