This does not fix your savefile if it has already been marked as a modded savefile. The first time you run the game with SFAE installed it will generate sfae.cfg within the installation folder with ...
Mods which you would like to install should be copied into the Steam\steamapps\common\House Party\Mods folder. For example Steam\steamapps\common\House Party\Mods\ItemRandomizer.dll.