This is not a new discussion, it has occurred before, most likely both here on the forum and across gaming tables.
It is difficult to write rules that are so unambiguous and iron clad that they can't be misinterpreted, deliberately or innocently misunderstood. IMHO it is a matter of using common sense and seeing what works and is fair.
It seems fairly rerasonable that Wound Penalties apply to Defense rolls, and eventually this is what kills you since lower Defense means higher Atk Advantage forthe opponent, which means higher Dam which is Soaked by the same amount as before, resulting most likely in larger wounds. Which affects the next combat round.
I know the Wound penalties are notes to affect both rolls and totals, but I bet it was not intended to apply twice!
For non-combat Soak apply Wound Penalties, because there was no rol before this where it could modify.
And suddenly you see that no mtter how the damage is applies, the Wound Penalties are applied once and make matters worse.
...except when someone casts a PeCo "inflict a Light Wound", these never kill you by themselves. OTOH once the poor victim has 42 Light Wounds go smack him upside the head, and even the Brawl 0, Dex -3, Str -3 magus can kill. But repeated use of '+1 damage' spells can eventually kill.