You can set the zoom level and default center point in the post editor to rewriting the following files on line 419 for ver.1.10.4.
plugins/geo-mashup/js/location-editor.js
If you want to display tokyo at zoom level 12, rewrite it like this.
map.setCenterAndZoom( new mxn.LatLonPoint( 0, 0 ), 2 );
↓
map.setCenterAndZoom( new mxn.LatLonPoint( 35.6980, 139.4130 ), 12 );
In this way, it may be rewritten when upgrading the plugin.
Please let me know if you know better ways.