Can she heal the karmic consequences of this harmful act?

This she has done in part, in the way she has redirected her life to come back into spiritual alignment once again. So all that she does now in using a spiritual focus and any acts of loving kindness will be rebalancing this debt. It is not something to fear or dwell on but can be thought of as motivation to go the extra distance, perhaps in looking for ways to contribute she might not otherwise bother with, but can be a way of building up spiritual capital, so to speak, and a karmic positivity to offset her debt. This the Law of Karma always takes into account. The point is never about causing pain and suffering per se, it is simply the reassignment of energies as they loop around to return them to the individual to be on the receiving end, but this is always done through gathering together all the intervening energies that have been created, and when a person has a reawakening of spirituality whether through pangs of conscience or a deeper reconnection via guidance from the higher self to come more completely into spiritual alignment as a conscious choice, there will be attention given to forestalling adverse consequences in order for the debt to be paid down in advance of being compromised in some way. This is because love is built into the system as well. The desire is always for learning and growth. Pain is a powerful motivator but is not the first choice of Creator—we would rather use the carrot than the stick. So if a person is on a loving path, they may well stay there, and forestall adverse consequences of many kinds from reaching them by staying one step ahead of the karmic payback through living their life dispensing love at a great enough frequency to pay down their debt, so to speak.