I would generally consider a lich Evil.
In the game they're probably Neutral because karma isn't actually based on morality in this game.
General morality
In most contexts both real and fictional, good and kind are roughly synonymous, as are evil and malicious. Animals do not clearly have either of these traits, which is why we do not see animals as good or evil no matter how viciously they tear each other apart.
Kindness and/or malice towards one's self is also covered by this. Liches are quite blatantly self-harmful both in body (undead) and in virtue (ambition), and therefore Evil even if they otherwise keep themselves to themselves.
Buuuut Liches are also prone to manipulating the bodies of the dead, or making people dead in order to do so, which is EEEEVIL.
Fractured morality
Karma is often seen as an ambiguous force of divine retribution, and Fractured is making this explicit by aligning karma with the divine interests of Arboreus ("Good") and Tartaros ("Evil"), who I presume are godly living planets. That is to say, Good and Evil are euphemisms for which side you're on.
Whatever Arboreus approves of is Good, and whatever Tartaros approves of is Evil. This is why mass-murdering characters (arbitrarily defined as) Evil, including say Demon newborns, is considered a Very Good act when in reality that is what an evil person masquerading as good does.
The condition of Lich-hood does not inherently require an allegiance to either of these planets, though, and therefore a Lich is likely to be allowed any (pretend) alignment they want.