I used clusterProfiler to perform GSEA, using log2 fold changes for my genesList. I then visualized the GSEA result, using the ridgeplot function from enrichplot, but am not sure what units the x-axis is in. Is the x-axis log2 fold change?
The enrichPlot docs are a little vague, but I think it's summarizing the "core enriched" (which I'm guessing are akin to "leading edge") genes for each gene set via (log2?) fold-change, so yes, I expect you are correct.
The dev hangs around the site too, so they may come and confirm (or correct) in time.