I would not doubt that some mix and match happens. I don't know if Tract would do it but Schott glass can mean several things.
Schott is famous for their borosilicate glass which is nice but I bet the Japanese and even Chinese can do plain borosilicate nearly as well if not as well as Schott. The expensive stuff that can change the optical design of the scope is the high and low dispersion glass. Not every lens needs high or low dispersion glass so if it's a plain borosilicate lens using Schott glass, that would be deceptive marketing. I know Schott has opened a glass foundry in China and there are differences between China Schott and Europe Schott. I bet Tract is using China Schott but it is either everything or they are using it for the high and low dispersion lenses.
Either way, my Tract Toric 30mm has nice glass.
I might be buying one of their 34mm scopes soon. I might go for one of Sig's new BDX models, I'm still up in the air, i want an ELR capable BDX scope but i also like good glass, if the Sig glass isn't a step up from first generation BDX, I'll probably buy the Tract.