I haven't seen any indication that there's a gravity limit for sprinkling. I have seen where Fermentis says you shouldn't sprinkle on wort that's at less than 68F. Example: https://fermentis.com/wp-content/uploads/2018/03/SafLager-W-3470.pdfHowever, under their E2U banner, that must be too hard to deal with, because it seems to have disappeared.