There is quite the divide in India, Egypt, Rome, and other regions between sites that make glass and sites that then turn that glass into beads. If this is the case, then any analysis of glass beads needs to take into account the fact that the beads themselves are (possibly) made in a completely different location than the glass they are made from. If we’re looking at the chemistry of the glass, then we need to be extra careful, since that chemistry won’t lead us to the location of where the beads were made; it will lead us to the site where the glass was made. Those are two very different things.
But then we have places like Southeast Asia, where glass and beads may well have been made at the same site. That leads to a whole set of other questions in terms of the extent of influence craftsmen from places like India had on the industry if the infrastructure is so different.
Putting that aside for the moment, we have several possibilities of manufacturing infrastructure. First, the glass was made at one location and then distributed to another where said glass was turned into beads. Second, we have an alternate of that (proposed in some of the literature on Egyptian glass) in which glass making, coloring the glass, and turning that glass into a finished product all occurred at different sites. And finally, glass and beads were both made at the same site.
And if that’s the case, then not only do we have issues with the chemical composition of the glass, we don’t know which of those scenarios a given manufacture site belonged to or if it belonged to another scenario we haven’t yet thought of. Sure, we can go off the surviving evidence for manufacture, but we would need access to the primary material, not just published sources.