I’m sure this is not an original theory, but when I saw the device i immediately thought that it may be a tool to sort / check the size of coins. Each size lines up to a known gold or silver piece. The largest hole allows all to be removed easily.
In western Europe, they would use scales to determine the weight of coin, since size itself doesn't mean much - that's logic used by modern day vending machines.
My measuring cups have markings are marked in paint, most of which has already worn away. Wouldn't stand a chance over millenia.
That said, you'd expect at least one or two to have informative notches for sizing. The universal dearth of text for such a common device is surprising.
And also, wouldn't they be a standard size for the region if they were for measuring coin? It sounds like each dodecahedron was different sizes.
I like the idea that the ratio between the incoming and outgoing holes allow you to get correct angles while looking through regardless of how the object is held (look through one of the smaller holes hold it far enough that the larger hole matches, and you have an exact angle viewer)