If you think of trade as sort of just randomly shuffling objects between nodes on a graph, given enough objects and enough time, you should see some examples of everything from everywhere, without any single person taking any object all the way from a to z.

I buy some perfume bottles at a port on the black sea, sell a bunch of them in anatolia, some trader picks them up a crate of them from a market in constantinople, sells them at a markup in italy, an aristocrat gives one to his wife, and then then gets appointed governor in Gaul, etc..

It stands to reason that the middle level important people who made strategic level decisions about things like military defenses, which roads to build up, etc, etc who's work was on the edge of the empire would move between the various points on its edge directly rather than traveling to/from Rome like a higher level person who reports to people in Rome would do. Some middle level political or military official probably bought the perfume around the same time they moved from the northeast to the northwest or had reason to travel there and brought it back as a souvenir or gift for their wife or something.

Sure, most rich people didn't travel or not that far but of those that did this is exactly the kind of place they'd wind up going to/from or passing through. The glass could have gotten there through a circuitous route as you described but I find it slightly more probable that it could have been transported there reasonably directly by its end user.

How direct or complex trade networks may be can be up for debate, but humans will be handing things off one way or another for sure.

The glass historian they contacted also thought it was a bit of a mystery and a special find.

What are your qualifications to say that they were wrong?