CDO

Dear CDO support team and users,
I am trying to use the snow cover data (Euro coverage) of the lsa-saf for a project but have problems defining the grid with cdo for further processing. These data are provided in HDF5 format in the MSG-seviri geostationary projection but I require them in NETCDF in lonlat. when using "cdo griddes" with one of the HDF5 files this is the result:

gridtype = generic
gridsize = 1107351
xsize = 1701
ysize = 651

The transformation fron HDF5 to nc4 does work without errors (in both cases with -import_cmsaf and whitout it).
The problems start, however, when I try to perform further computations since cdo cannot operate with the "generic" grid type. The solution that I found in the Forums was to use -setgrid and a file defining the input grid.
following the documentation from the LSA-SAF I created the following file:

gridtype = lonlat
gridsize = 1107351
xsize = 1701
ysize = 651
xname = lon
xunits = "degrees"
yname = lat
yunits = "degrees"
xfirst = -46.0475
xlast = 78.338
yfirst = 81.2648
ylast = 34.4869

and with it the following line works without errors:
cdo -f nc4 copy -setgrid,seviri_grid_euro.txt HDF5_LSASAF_MSG_SnowC1U_Euro_201401311200 test_out.nc
After setting this grid I am able to make further operations with test_out.nc but the spatial coverage is unfortunatelly wrong (see attached image. the raster should actually match with the coastlines).
I suppose the error is that the original file is in a Geostationary projection and with my file I was unable to provide this information to cdo. It was impossible for me to find an example of how this file should actually looks like. I tried changing the gridtype but there were not many documented options (e.g. curviliniear, unstructured)and further calculations such as changing resolution and cliping with a bounding box ended with errors. I would highly appreaciate if someone could tell me which is the appropriate way to set the grid in this case and/or any hints in case someone has experience with the lsa-saf data and cdo.
thank you in advance!
Best Regards