I've played through the game a couple times and every time I get #74 from the lonely Urotsuki event. That being said, I don't know what exactly makes you get the wallpaper. I think you can't get squished at the end, and maybe you need to have all the other wallpapers related to the event first?
And I'm also not sure on 97. It's the one wallpaper I've never gotten, even though I'm pretty sure I've encountered all the things too (including using a lantern on the blobs). :\