You like Retrodays but you don't want to squint at tiny sprites? Well here's a solution: GiantDays! Basically Nerodays tileset upscaled and redrawn to 20x20 sprites
It's currently available in the tileset repo
https://github.com/I-am-Erk/CDDA-Tilesets/pull/2098
and should get shiped with the game soonish
Catapult (or any launcher for that matter) has no way to know if the mod downloaded is compatible with your version of the game so you're decently likely to get something broken