I think you may be interpreting the applied circa dates more literally than they were meant. We're all accustomed to the speed of the age we live in and it makes it harder to relate to the pace of the past. Our simple exchange of two messages was near instantaneous. In 1720, the same two messages from NY to HI, would have taken four years or so to have been sent and responded to. In the early 18th century (and then some), changing styles and forms in the decorative arts moved at a comparably snail paced speed. To illustrate, here is a link to a similar bowl (by B. Le Roux) catalogued as circa 1690â€“1700. http://m1.freeshare.us/163fs836625.jpg
and another (by C. Kierstede) catalogued as circa 1700â€“1710.http://www.metmuseum.org/toah/ho/09/na/hob_38.63.htm
The Kierstede bowl, though a good circa
20 years the junior of the Soumaine bowl is, aside from extraneous repousse decoration, virtually identical.
The point I am laboring to make is that for American silver of this period, labeling pieces as ca. 1720, ca. 1723, or ca. 1730 is basically giving them all the same date.