this relates to this issue SNAP 8 - cannot save vectors in dim
I don’t think it is possible at the moment to re-import a csv generated by SNAP. But you can load it into QGIS as suggested below (make sure you are selecting the correct coordinate reference system), and then save them as a shapefile. This can then be imported in SNAP again. Not very straightforward, but at least allows you to use your digitized areas
