Really interesting Cagney. Thank you for posting links.
The different colour blues on the same piece is strange to me:
https://jeffreysevans.com/auction/free-blown-and-blown-molded-sawtooth-vase-with-rare-decoration-ball/Other odd things that occur to me - the ball on this doesn't seem to 'go with' the piece:
https://jeffreysevans.com/auction/free-blown-and-blown-molded-sawtooth-vase-with-extremely-rare-decoration-ball/And the domed foot - is that normal for Sandwich glass? Is it hollow I wonder?
Re Christine's vase - I would search French first I think, partly because of the green of the opaline and partly because the ribbed and dotted design on the body is something they used on a particular type of vase called a Jasmine vase. That is a different shape completely to Christine's item but it's still a design link that would not make me discount a French maker.
Some examples here:
https://www.pressglas-korrespondenz.de/aktuelles/pdf/pk-2017-1w-boschet-jasminvase-korb-gruen-1840.pdfAlso the design of the foot.
That said, I know nothing about American glass so there is a huuuuge body of glass that I couldn't even contemplate trying to compare to. I'd think it more unlikely to find American glass here however with international sales I guess it becomes more likely than it was in the past.
m