Here is a link to the item.(admin edit)
There is a very similar example of the same workshop in an important Foundation in Switserland. That one has no markings.
Object is vetted by different experts and they all agree on the age, 13th -14th century.
The markings can be of a later date. Import - customs,... I have really no idea.
I searched in next book:
Der Goldschmiede Merkzeichen (Band 4): Ausland und Byzanz
But I did not find anything similar.