Hello
I am going to dive into waters that I am not real comfortable with i.e. pre EAPG era tableware. Heck, I am not even comfortable with flint EAPG tablewares. On second thought, I am just going to dip my toe in.
Barlow and Kaiser indeed show what appears to be the plate in question in Glass in Sandwich Vol 1 as figure 1088. They show two other plates (1089 and 1366) in a similar but distinctly different pattern, one of which is referenced to the Lee-Rose book "American Glass Cup Plates". The main design difference from your example is that the central area inside the four large medallions is not stippled and the decorative bit in the direct centre is different in the latter two plates. Barlow and Kaiser do not indicate that shards were found at the site for figure 1088 and do not list this as a pattern that can be documented (catalog, price lists, shards, etc.) as being made at the factory. Lee-Rose, in turn, show several plates with a shell border, none of which match the plate of interest but several of which are clearly related to the latter two plates in Barlow and Kaiser. Spillman shows yet another variant as Figure 301 in "American and European Pressed Glass in the Corning Museum of Glass".
It looks like several variations of the same design were being made at that early date. Typically this means, at least in later years, that there is a high probability that several factories were involved.
Sid