Just pointing out that any "evil" that shadowheart commited is pure speculation right now. The only thing we know for sure she did was stealing the gith artifact, and we don't even know for sure what this artifact is. Sure she is Shar worshiper, but we have no idea what service (if at all) she provided her goddess.
The talk about atonement is somewhat premature if we don't even know what she needs to atone for
Also @Tulkash01, when I say reward I definitely do not mean material reward. I mean some sort of abstract reward, for example society applauding and giving you credit for having abandoned your evil past and become good now. One should not get any credit or be celebrated for doing penance for one's past wrongs. And I definitely agree with the Lord of the Rings example you give; that's *exactly* how I see penance and redemption happening for anyone who's committed capital crimes.