This isn't a variegated lilac. It's a white-flowered tree lilac that has been subjected to vast hours of sunshine this summer. All the branches receiving day-long sun have leaves that have yellowed along the margins. I don't recall this ever happening before, and I'm guessing it's sun-wrought. The leaves are slightly curled, but nonetheless attractive.
This is the sole solomon's seal plant that pokes out from beneath the lilac (the others are in full shade). It too, and more unpleasantly, has been impacted by the intense insolation of July and early August.