1) the resident lawfully fired upon a home intruder
2) the bullet used in the resident's weapon was of a pistol caliber
3) the bullet penetrated the walls of the home
4) the bullet struck an innocent bystander
5) the bystander filed a lawsuit against the lawfully acting resident (the resident was firing at an intruder, not shooting the bystander)
6) The bystander won the lawsuit and/or a settlement
7) if conditions 1 through 6 apply, then the case applies to this thread.
Does the situation really hinge on #3? I would think striking an innocent bystander is striking an innocent bystander, regardless of whether it was cause by over-penetration, missing, accidental discharge, or shooting through a wall as a result of any of these. The question is not much different from what rounds to use when you are shooting in a public place.
Conceptually, though, it's another magic bullet question, asking "what bullet will give me <insert contradictory expectations here, like kill the bad guy, stop hairloss, pick up after my dog, have no recoil, and still be cheap enough to practice with at the range 3C a week>"
I see this question of what type of building you live in and what rounds may or may not penetrate the wall as no different from any other situation. Remember the episodes of TBD where they mentioned making sure you have a solid backstop and the more more recent one of making sure no one else was behind the target? Since you can't know who is on the other side of the wall, it's important that you have a solid backstop
It's basic gun safety: make sure what you are shooting at and what is beyond it. A drywall or plaster partition, even a fire rated one with a couple layers of drywall, isn't a safe backstop. If you don't have a sufficient backstop (which in residential construction, you're talking poured concrete, multiple wythes of brick, or a bookcase facing the right direction with a lot of books on it), you can count on possibly hitting someone you did not mean to.
The real question is not "what round will magically protect possible innocents?" It's "what can I do to avoid accidentally shooting innocent neighbors?" That mostly means installing an alarm, having a cell phone by the side of the bed, buying decent locks (ok, now with the basics out of the way, we can talk weapons), selecting a good safe room, pre-planning your lines of fire, and spending enough time practicing ("war gaming") in your house that you know what a "safe shot" in your house is.