What about *before* they become president of the LR?
Some time last year I noticed that the last several years of the Harvard Law Review is now online so I took a look at it. I checked the last seven presidents of the review and found that none of them had written articles for the review (even before they were president), although a couple of them were credited with assistance in footnotes. It turns out that the "articles" in the HLR are all written by famous law professors, not students who don't even have their JD. There are other parts of the HLR that review current legal cases of interest, etc. These parts are put together by the editors of the review, perhaps including the president, but all these parts are written anonymously.
BTW a relative of mine who attended another law school did publish an article in their law review under his name while he was a student, but it appears that this is not at all the usual practice at the HLR.