I had never heard the term "frog" (in this context!) until I joined this Board. Sowerbys, Davidsons and, I think, the rest of the North East pressed glass industry certainly didn't use the word. The round or oval, chunky or cauliflower-shaped things with holes through them were called flower blocks, always abbreviated to blocks. Everything else, whether flat discs with holes or star shaped or shaped like a DIY fire escape or with a lady sitting on top was called a flower holder, usually just holder.
Whether the word frog was used before my time and has been resurrected or came from some other part of the industry (or pottery?) or whether block and holder were too boring for the trendies who took over the world later I know not!