That is a good idea, but tracking each converter's serial number and manually configuring each machine with it is not practical in a manufacturing process.
However I see how a hybrid solution could work. Our current approach with PHYSDEVPATH does work if all devices are plugged in, so knowing that this the case we could use it to automatically generate a one time mapping from a USB serial number to location. It is still a pain because the mapping will have to be re-generated if a converter is replaced (and they do fail out in the field, being the cheap pieces of garbage that they are), but it is a conceptually robust solution.
Sigh, I do miss the olden days of ISA, i2c and even PCI. Now PCIE has been relegated to being a "server technology" in practice.