I don't think you can have your cake and eat it too
To diffuse light and make it 'softer', generally you're talking about making a big light source. Things like softbox, bounce card, etc.
What you're making looks like the shaped cone of a loudhailer.
better range looks possible, but diffused light doesn't seem to be part of the plan.
Anyway, good job for trying out this DIY project! I'm sure it will still come in useful somehow
Can check out this video
Though it's mainly referring to studio strobes, the concept of softer light from a larger source at close proximity to the subject probably applies quite appropriately.