Okay, try loading this pk3 instead of the main release jphud.pk3: https://www.dropbox.com/s/tzl1lh9fpmbbxaz/jphud_smoothdoom.pk3?dl=0
Smooth Doom defines its own custom weapons so the player doesn't have the ones that my HUD was expecting. I generalized it a little bit, but only just enough to make this custom version of it.