First of all, I love GOG Galaxy, Being a game client of a program and also library manager I consider it the only launcher you'll ever actually need to open, but like 2 weeks ago I decided to add my itch.io games and ofc because itch is being itself (an indie game platform), The amount of unknown games are taking half of my library, I'm not gonna blame GOG's sources/database for that as I know how difficult it is to add every garage indie shovelware game to a single database but having a filter button to auto hide unknown/unrecognized games would be nice, As well as a link or an address to the original page of the unknown game so you can know what it is and add details for it manually, As of now there is no way to even know which one is which and they are too many to hide them manually one by one

One last thing, The "Share Feedback" button in the Galaxy menu links to a form that doesn't work no more

I believe GOG Galaxy pulls data from IGDB. If you manually create an entry for a game there, it should hopefully be reflected in the application as well. That was fixed in version 2.0.52 Preview, released July 12th. If you want that update, you need to go into Settings - General and check "Be the first to try out new features..."