Hi Maxim,
Thanks for the link, it’s quite interesting. It’s good to see that I’m not the only one who ran into this issue. I think I’ll try to contact the author of that blog and ask whether he has additional info for the SLSTR grid.
Scihub support (eosupport@copernicus.esa.int)
Oh those guys already know me. 
I asked them recently a couple of questions, mainly technical ones regarding the Sentinel SAFE specification. They are helpful but not too fast. 
If I don’t find an explanation for my issue I’ll ask them for sure.
Please let us know if you find something interesting
Of course.
Cheers,
Zoltan