Hi, Coleen,
It looks like your tileset.txt (at least on the 24x24 version) references “gfx/Coleen24Tileset”, but the leading “gfx/” is not required as Cata fills that in automatically. Here’s a corrected tileset.txt for ya:
NAME: Coleen
VIEW: Coleen's
JSON: Coleen24Tileset/tile_config.json
TILESET: Coleen24Tileset/Coleen.png
I haven’t looked at the 32x32 version, but if it has the same kind of setup, it’ll also need correcting.