To convert POIs from gpx-files (say Osmand) to Mapfactor it's not advisable to use digger. You don't need a mca-file but an xml-file (favourites.xml) in this folder: Android/Data/com.mapfactor.navigator/files/navigator. To create an xml-file use GPSBabel.
For me it's not suitable to have hundreds of POIs among my favorites. The advantage of POIs in mca format is that You always can see them on Your screen, be it in planning or in navigation mode.
With digger, I created a mca file with all mountain passes of the alps, including an own icon. It's such a joy to hop from pass to pass, just by tapping on the icon and select it as destination in the bottom menu popping up.