Coming back to the filled-in slots in the shotgun rib:
the Wiener Schnäpper basically needed 2 tiny crossbars in dovetail slots, as seen here, 2nd picture from top
https://www.fernglasmuseum.at/museum/reichert_wien_zielfernrohr/reichert_wien_zielfernrohr.html
Distance between the slots is defined by action type and scope, can be quite close together as in the example.
(this does not look stable and mechanically sound to our eyes..... there must be reasons why this way of mounting a scope is extinct)

With monogram or not, this gun quite probably was made to order. And whatever the gunsmith thinks or prefers, in the end he will produce what the customer wants (more or less at least, same today as back in 1914). And we may never know what the customer wanted to achieve with this combo, but of course we may continue to speculate.