It's not a matter of Origin. I've uninstalled a lot of Steam games, Galaxy insists on showing them all in the "installed" section (restarted Galaxy, restarted computer, no change). But of course, when you select the individual game, both "play" and "uninstall" functions are greyed out. So Galaxy knows they're not there. But still ignores it. Because.

That's helpful. But hey, GOG made it abundantly clear that they'll come kill us in our sleep if we don't install their optional client, so, living with that...