I do not know. It appears you download a map file using that app. The offline map seems to be a map on an OpenStreetMap tile base, perhaps in kml format. Do you have the kml file? I seem to recall the that it is possible to extract the hiking map trail to a LineString. If that is true, then the following applies and you might be able to post some of the data from that map to the Map component:
You can convert kml to json or json to kml. How? Here is a beginning https://groups.google.com/forum/#!category-topic/mitappinventortest/app-inventor-extensions/DqEeorciOC0 These links provide some other potential ideas.
Is this possible? What you do depends on why you need the coordinate information in kml format. https://developers.google.com/kml/documentation/kml_tut and why you need to work with Google Earth. KML traks can be displayed (with some transformation) on the Map component as a LineString.
A location in kml format looks like
Is this what you need to know?