remember that many glassworkers have traveled all over the world and work in many different factories. I know poersonally of several of the great Murano artists that spent time in Mexico for several years training Mexican workers nand doing work in Mexico. Also several UK and US people that have moved to China and run factories there after they trained the Chinese. The similiarities may because they are actually made by some of the same artisans or people that are trained by them. People travel a lot anymore and it's not unusual for some of the artists to work in many parts of the world.
I have a friend who many years ago worked for the following companies in the US, Blenko, Fenton, Indiana Glass, his own shop and several others. Who knows that many of the Italians may be doing some work in other countries since many of the Italian companies and studios have closed or downsized or the Romanians may have worked in Murano at one time or another and developed the same skills.
I currently have a friend that is doing major consulting and training work with a small Chinese company and he lives in the US. He's teaching them exotic color formulations, polishing techniques and all sorts of other things and some of the people from the factory are coming to the US to be trained.
I have another friend that has developed glass factories in Mexico and China after selling his factory in the US.
I'm not sure that the country of manufacture is that important as it is that the pieces are good pieces of art.
Dale Chihuly rented factories in many different countries for short periods of time to make some of his larger installations. including Waterford, and factories in Finland, Murano, and Japan.