Since you totally ignored the point of my post there about this being for one type of PC (i.e. non-proficient) and not for others (i.e. proficient), it seems like you are being like a dog with a bone. It doesn't matter if the bone is old, that dog is not going to let go.
I think it's more a case of "you and I don't speak the same language. "
That must be it, because, as far as I can tell, not only have I not ignored your point, I've addressed it several times throughout this thread. In fact, in my estimation, the mechanic I specifically asked you about at the end of my last post addresses that point among others. Apparently you disagree, but since we apparently have a language barrier to overcome, I certainly don't want to put words in your mouth.
I'm trying to discern your intent here. Are you trying to fix the math (which you claim you are not, but this solution appears to go right into that wheelhouse)? Or are you trying to come up with a narrative solution to a bonus to a save (which your solution is not really trying to do equally for all PCs)?
Neither. I have been clear about my intent on the multiple occasions I have explained it.
At least, my words seem clear to me. But since you and I aren't speaking the same language, may I posit that my intent doesn't matter.
For example, +2 to any save with a reaction if they give a good narrative way to try to avoid the spell (best because it does not mess with the math a lot and it handles prof vs. non-prof issue).
Or even (if you feel like being real generous), advantage to any save with a reaction if they give a good narrative way to try to avoid the spell (not quite as good since it steps on the toes of Inspiration, one player worked for Inspiration, but nearly everyone gets it for saves anyway).
Again with the language barrier.
"Narrative complication/consequence" does not have anything to do with any of that stuff. It means something happens in the context of the story of the game.
Perhaps an example would suffice.
DM: "Make a Dex save to minimize the damage from the goblin shaman's fireball."
PC: "Crap. I'm not proficient. If I leap down that pit, can I add Athletics?"
DM: "Sure, at the cost of your Reaction, but if you fail, you'll take falling damage on top of the fireball damage. And the goblin that's down there will eat your puppy."
But, you seem to be married to your solution as opposed to looking for better ways. Defending it instead of seeing its weaknesses and looking for better.
Assuming that "something better" doesn't just mean "don't do it," lay it on us. As long as you have something constructive to add, I'm all ears.