I use MapAnalyst, a FOSS tool for the accuracy analysis of old maps. The tool creates, between else, Distortion Grids and Displacement Vectors/Circles (see screenshot). These can be exported as Shapefiles.
However, when I export from MapAnalyst, the resulting Shapefile comes with no information about the CRS. Grids and vectors are displayed near NULL island. I can manually set a CRS, but whatever CRS I try (
EPSG:3857 as the OSM basemap,
EPSG:4326 etc.), it does not seem to be the correct one.
How can Grids and Vectors be exported from MapAnalyst to be able to visualize them correctly in QGIS?