After going through your post, I was able to replicate the same issue with a different “Open Street Map” File. However, there does not seem to be any way to move the map around in the import window. The import tool centres the map based on the Geographic Reference and by default opens the map with all selectable roads visible.
In the above picture, the Geographic Reference is visible, along with the grey borders of available roads for an example OSM. Using the zoom and select option in the top right, the required roads can be selected.
A workaround to moving the map around to have fine grained selection is to import the rough areas of the road required. Then, once they are imported into the Scenario Canvas, there is the ability to freely zoom and pan. Here, one can drop the unnecessary roads and fine tune the selection.
The above Scenario is imported from the Open Street Map Example which can be opened using the following command:
openExample('driving/ImportOpenStreetMapDataIntoDrivingScenarioExample')