Enemies will only be sent flying if they are dealt a high enough amount of damage. In vanilla Doom gameplay, this can only be achieved with the Berserk Pack, Rocket Launcher, the BFG9000 or explosive barrels. Or typing MDK into GZDoom's console.
This mod is best combined with mods that allow you to deal high amounts of damage to enemies, such as Broadsword Jim, Obliterator, Trailblazer, Russian Overkill and so on.
I would rather not use Treasure Tech sounds in this mod, as that mod is still technically in-development.