Regarding these Murano glass lamps & I have some experience having sold approx 20 good ones over the years & not one of them could be positively attributed. Most U.S. final stage lamp manufacturers after WWII did not manufacture the glass components of their lamps…they subcontracted with glass manufacturers, some domestic, some foreign (imports), for glass parts & had them shipped for final assembly so identifying whom did what for whom is pretty much impossible since subcontracted job records were not kept by the vast majority of either glass manufacturers or final stage lamp manufacturers.
When it comes to Murano glass parts for lamps (and keep in mind 95% of the times just the glass was shipped not a complete lamp), it could be almost anyone...just throw out names, Seguso, Toso, Barbini, I could go on & on, who designed & manfactured the glass parts for assembly so I would not even hazard a guess.
This may give you a better idea of what you are up against when it comes to attribution of glass used in lamps in many cases.